Ua tsaug rau koj tuaj xyuas Nature.com.Qhov browser version koj siv tau txwv CSS kev txhawb nqa.Rau qhov kev paub zoo tshaj plaws, peb xav kom koj siv qhov browser tshiab (lossis lov tes taw Compatibility Hom hauv Internet Explorer).Nyob rau lub sijhawm no, txhawm rau ua kom muaj kev txhawb nqa txuas ntxiv, peb yuav ua rau lub xaib tsis muaj qauv thiab JavaScript.
Cov evolution ntawm microbial parasites koom nrog kev tawm tsam ntawm kev xaiv ntuj, uas ua rau cov kab mob ua kom zoo dua qub, thiab caj ces drift, uas ua rau cov kab mob ploj zuj zus thiab tsim cov kev hloov pauv tsis zoo.Ntawm no, txhawm rau kom nkag siab tias qhov kev tawm tsam no tshwm sim li cas ntawm qhov ntsuas ntawm ib qho macromolecule, peb piav qhia txog cov qauv cryo-EM ntawm ribosome ntawm Encephalitozoon cuniculi, kab mob eukaryotic nrog ib qho ntawm cov genomes tsawg tshaj plaws hauv qhov xwm txheej.Qhov kev txo qis heev ntawm rRNA hauv E. cuniculi ribosomes yog nrog los ntawm cov qauv kev hloov pauv uas tsis tau pom dua, xws li kev hloov pauv ntawm yav dhau los tsis paub fused rRNA txuas thiab rRNA tsis muaj bulges.Tsis tas li ntawd, E. cuniculi ribosome tau dim ntawm kev poob ntawm rRNA fragments thiab cov proteins los ntawm kev txhim kho lub peev xwm los siv cov molecules me me raws li cov qauv ua qauv ntawm degraded rRNA fragments thiab cov proteins.Zuag qhia tag nrho, peb qhia tau hais tias cov qauv molecular ntev xav kom txo qis, degenerate, thiab raug rau cov kev hloov pauv tsis zoo muaj ntau cov txheej txheem them nyiaj uas ua rau lawv ua haujlwm txawm tias muaj kev cog lus molecular heev.
Vim tias feem ntau pawg ntawm cov kab mob microbial muaj cov cuab yeej molecular tshwj xeeb los siv lawv cov tswv, peb feem ntau yuav tsum tsim kho cov tshuaj sib txawv rau cov pab pawg sib txawv ntawm parasites1,2.Txawm li cas los xij, cov pov thawj tshiab qhia tias qee yam ntawm cov kab mob parasite evolution yog sib koom ua ke thiab muaj kev kwv yees loj heev, qhia txog lub hauv paus muaj peev xwm rau kev kho mob dav dav hauv cov kab mob microbial 3,4,5,6,7,8,9.
Cov haujlwm yav dhau los tau txheeb xyuas qhov kev hloov pauv hloov pauv hauv cov kab mob microbial hu ua genome txo lossis genome decay10,11,12,13.Kev tshawb fawb tam sim no qhia tau hais tias thaum cov kab mob tso tseg lawv txoj kev ua neej dawb thiab dhau los ua kab mob hauv lub cev (lossis endosymbionts), lawv cov genomes tau qeeb tab sis zoo heev metamorphoses ntau lab xyoo 9,11.Nyob rau hauv tus txheej txheem hu ua genome decay, microbial parasites sau deleterious mutations uas tig ntau yam tseem ceeb yav tas los noob rau hauv pseudogenes, ua rau gradual noob poob thiab mutational collapse14,15.Qhov kev sib tsoo no tuaj yeem rhuav tshem mus txog 95% ntawm cov noob hauv cov kab mob hauv lub cev qub tshaj plaws piv rau cov tsiaj muaj sia nyob sib ze.Yog li, kev hloov pauv ntawm cov kab mob hauv lub cev yog kev sib ntaus sib tua ntawm ob lub zog tawm tsam: Darwinian ntuj xaiv, ua rau kev txhim kho cov kab mob, thiab lub cev qhuav dej ntawm cov genome, ntuav cov kab mob mus rau hauv oblivion.Yuav ua li cas tus kab mob tau tswj kom tshwm sim los ntawm kev sib ntaus sib tua no thiab khaws cov haujlwm ntawm nws cov qauv molecular tseem tsis paub meej.
Txawm hais tias cov txheej txheem ntawm genome decay tsis to taub tag nrho, nws zoo nkaus li tshwm sim vim yog nquag genetic drift.Vim tias cov kab mob cab nyob hauv cov neeg me, asexual, thiab noob caj noob ces, lawv tsis tuaj yeem tshem tawm cov kev hloov pauv uas qee zaum tshwm sim thaum DNA rov ua dua.Qhov no ua rau irreversible tsub zuj zuj ntawm teeb meem kev hloov pauv thiab txo cov parasite genome.Raws li qhov tshwm sim, tus kab mob tsis tsuas yog poob cov noob uas tsis tsim nyog rau nws txoj sia nyob hauv ib puag ncig intracellular.Nws yog qhov tsis muaj peev xwm ntawm cov kab mob cab kom ua tau zoo tshem tawm cov kev hloov pauv tsis zoo uas ua rau cov kev hloov pauv no mus rau thoob plaws hauv genome, suav nrog lawv cov noob tseem ceeb tshaj plaws.
Ntau ntawm peb cov kev nkag siab tam sim no ntawm kev txo cov genome tsuas yog ua raws li kev sib piv ntawm cov kab ke genome, nrog tsawg dua cov kev hloov pauv hauv cov molecules tiag tiag uas ua haujlwm tu vaj tse thiab ua lub hom phiaj siv tshuaj.Cov kev tshawb fawb sib piv tau pom tias lub nra ntawm kev hloov pauv hauv cov kab mob microbial zoo li ua rau cov proteins thiab nucleic acids ua rau tsis sib haum thiab sib sau ua ke, ua rau lawv ntau dua chaperone nyob thiab kub siab rau qhov kub 19,20,21,22,23.Tsis tas li ntawd, ntau yam kab mob - kev hloov pauv ywj pheej qee zaum sib cais los ntawm ntau npaum li 2.5 billion xyoo - tau ntsib qhov tsis zoo ntawm cov chaw tswj xyuas zoo hauv lawv cov protein synthesis5,6 thiab DNA kho mechanisms24.Txawm li cas los xij, me ntsis paub txog qhov cuam tshuam ntawm kev ua neej nyob hauv lub cev ntawm tag nrho lwm yam khoom ntawm cellular macromolecules, suav nrog kev hloov pauv ntawm cov molecular mus rau lub nra hnyav ntawm kev hloov pauv.
Hauv kev ua haujlwm no, txhawm rau nkag siab zoo dua txog kev hloov pauv ntawm cov protein thiab nucleic acids ntawm cov kab mob hauv lub cev, peb txiav txim siab cov qauv ntawm ribosomes ntawm intracellular parasite Encephalitozoon cuniculi.E. cuniculi yog cov kab mob zoo li cov kab mob uas muaj nyob hauv ib pawg ntawm cov kab mob parasitic microsporidia uas muaj cov genomes eukaryotic me me thiab yog li ntawd siv los ua cov qauv kab mob los kawm txog genome decay25,26,27,28,29,30.Tsis ntev los no, cryo-EM ribosome qauv tau txiav txim siab txo qis genomes ntawm Microsporidia, Paranosema locustae, thiab Vairimorpha necatrix31,32 (~ 3.2 Mb genome).Cov qauv no qhia tias qee qhov kev poob ntawm rRNA amplification yog them los ntawm kev txhim kho cov kev sib cuag tshiab ntawm cov neeg nyob sib ze ribosomal proteins los yog nrhiav tau ntawm msL131,32 ribosomal proteins tshiab.Hom Encephalitozoon (genome ~ 2.5 lab bp), nrog rau lawv cov txheeb ze ze tshaj plaws Ordospora, ua kom pom qhov kawg ntawm kev txo qis ntawm genome hauv eukaryotes - lawv muaj tsawg dua 2000 protein-coding noob, thiab nws xav tias lawv cov ribosomes tsis yog tsuas yog tsis muaj rRNA nthuav tawm cov kab mob uas cuam tshuam rau qee yam kab mob (rRNA). somes) kuj muaj plaub ribosomal proteins vim lawv tsis muaj homologues hauv E. cuniculi genome26,27,28.Yog li ntawd, peb tau xaus lus tias E. cuniculi ribosome tuaj yeem nthuav tawm cov tswv yim tsis paub yav dhau los rau kev hloov pauv ntawm cov molecular rau genome decay.
Peb cov qauv cryo-EM sawv cev rau qhov tsawg tshaj plaws eukaryotic cytoplasmic ribosome los ua tus cwj pwm thiab muab kev nkag siab txog yuav ua li cas qhov kawg ntawm kev txo qis ntawm genome cuam tshuam rau cov qauv, sib dhos, thiab kev hloov pauv ntawm cov tshuab molecular uas yog ib qho tseem ceeb rau lub cell.Peb pom tias E. cuniculi ribosome ua txhaum ntau ntawm cov ntsiab cai dav dav ntawm RNA folding thiab ribosome los ua ke, thiab nrhiav tau ib qho tshiab, yav tas los tsis paub ribosomal protein.Tsis tau xav txog heev, peb qhia tau hais tias microsporidia ribosomes tau hloov zuj zus lub peev xwm los khi me me molecules, thiab xav tias truncations nyob rau hauv rRNA thiab cov proteins ua rau evolutionary nrhav uas thaum kawg yuav muaj txiaj ntsig zoo ntawm ribosome.
Txhawm rau txhim kho peb txoj kev nkag siab txog kev hloov pauv ntawm cov protein thiab nucleic acids hauv cov kab mob hauv lub cev, peb txiav txim siab cais E. cuniculi spores los ntawm kab lis kev cai ntawm cov kab mob mammalian hlwb txhawm rau txhawm rau ntxuav lawv cov ribosomes thiab txiav txim siab cov qauv ntawm cov ribosomes.Nws yog ib qho nyuaj kom tau txais ntau tus kab mob parasitic microsporidia vim tias microsporidia tsis tuaj yeem coj mus rau hauv cov zaub mov nruab nrab.Hloov chaw, lawv loj hlob thiab tsim tawm tsuas yog hauv cov tswv tsev cell.Yog li ntawd, kom tau txais E. cuniculi biomass rau ribosome purification, peb kis tau tus kab mob raum kab mob RK13 nrog E. cuniculi spores thiab coj cov kab mob no rau ob peb lub lis piam kom tso cai rau E. cuniculi loj hlob thiab ntau.Siv cov kab mob cell monolayer txog li ib nrab ib square meter, peb muaj peev xwm ntxuav tau txog 300 mg ntawm Microsporidia spores thiab siv lawv cais ribosomes.Tom qab ntawd peb cuam tshuam cov purified spores nrog iav hlaws thiab cais cov crude ribosomes siv stepwise polyethylene glycol fractionation ntawm lysates.Qhov no tau tso cai rau peb tau txais kwv yees li 300 µg ntawm raw E. cuniculi ribosomes rau kev txheeb xyuas cov qauv.
Tom qab ntawd peb tau sau cov duab cryo-EM siv cov qauv ribosome uas tau tshwm sim thiab ua tiav cov duab no siv lub qhov ncauj qhov ntswg sib xws rau cov ribosomal subunit loj, lub taub hau me me, thiab cov subunit me me.Thaum lub sijhawm txheej txheem no, peb tau sau cov duab txog 108,000 ribosomal hais thiab suav cov duab cryo-EM nrog kev daws teeb meem ntawm 2.7 Å (Cov duab ntxiv 1-3).Peb mam li siv cov duab cryoEM los ua qauv rRNA, ribosomal protein, thiab hibernation factor Mdf1 txuam nrog E. cuniculi ribosomes (Fig. 1a, b).
ib tug qauv ntawm E. cuniculi ribosome nyob rau hauv complex nrog lub hibernation factor Mdf1 (pdb id 7QEP).b Daim ntawv qhia txog hibernation factor Mdf1 txuam nrog E. cuniculi ribosome.c Daim ntawv qhia theem nrab piv piv cov rRNA zoo nyob hauv Microsporidian hom kom paub cov qauv ribosomal.Cov vaj huam sib luag qhia qhov chaw ntawm cov khoom siv hluav taws xob rRNA (ES) thiab ribosome active sites, nrog rau qhov chaw txiav txim siab (DC), lub voj sarcinicin (SRL), thiab lub chaw peptidyl transferase (PTC).d Lub electron ceev sib xws rau peptidyl transferase chaw nruab nrab ntawm E. cuniculi ribosome qhia tias qhov chaw catalytic no muaj cov qauv zoo ib yam hauv E. cuniculi parasite thiab nws cov tswv, suav nrog H. sapiens.e, f Qhov sib thooj electron ceev ntawm lub decoding center (e) thiab schematic qauv ntawm lub decoding center (f) qhia tias E. cuniculi muaj residues U1491 es tsis txhob A1491 (E. coli numbering) nyob rau hauv ntau lwm eukaryotes.Qhov kev hloov pauv no qhia tias E. cuniculi tuaj yeem nkag siab rau cov tshuaj tua kab mob uas tsom rau qhov chaw nquag no.
Nyob rau hauv sib piv rau yav tas los cov qauv ntawm V. necatrix thiab P. locustae ribosomes (ob qho tib si qauv sawv cev tib lub microsporidia tsev neeg Nosematidae thiab zoo ib yam li ib leeg), 31,32 E. cuniculi ribosomes undergo ntau txheej txheem ntawm rRNA thiab protein fragmentation.Ntxiv denaturation (Cov duab ntxiv 4-6).Hauv rRNA, qhov kev hloov pauv loj tshaj plaws suav nrog kev poob tag nrho ntawm cov amplified 25S rRNA fragment ES12L thiab ib nrab degeneration ntawm h39, h41, thiab H18 helices (Fig. 1c, Supplementary Fig. 4).Ntawm cov ribosomal cov proteins, qhov kev hloov pauv loj tshaj plaws suav nrog kev poob ntawm eS30 protein ntau thiab ua kom luv ntawm eL8, eL13, eL18, eL22, eL29, eL40, uS3, uS9, uS14, uS17, thiab eS7 Figures (Suppures).
Yog li, qhov kev txo qis ntawm cov genomes ntawm Encephalotozoon / Ordospora hom yog tshwm sim nyob rau hauv lawv cov qauv ribosome: E. cuniculi ribosomes muaj kev poob siab tshaj plaws ntawm cov ntsiab lus protein nyob rau hauv eukaryotic cytoplasmic ribosomes raug rau cov yam ntxwv ntawm tus yam ntxwv, thiab lawv tsis txawm muaj cov rments RNA uas tsis tsuas yog nyob rau hauv cov protein ntau, tab sis kuj nyob rau hauv fragility. s lub neej.Cov qauv ntawm E. cuniculi ribosome muab thawj cov qauv molecular rau cov kev hloov pauv no thiab nthuav tawm cov xwm txheej evolutionary uas tau raug saib xyuas los ntawm ob qho tib si sib piv genomics thiab kev tshawb fawb ntawm intracellular biomolecular qauv (Ntxiv daim duab 7).Hauv qab no, peb piav qhia txhua yam ntawm cov xwm txheej no nrog rau lawv cov keeb kwm kev hloov pauv thiab lawv muaj peev xwm cuam tshuam rau kev ua haujlwm ribosome.
Tom qab ntawd peb pom tias, ntxiv rau qhov loj rRNA truncations, E. cuniculi ribosomes muaj rRNA variations ntawm ib qho ntawm lawv qhov chaw nquag.Txawm hais tias lub chaw peptidyl transferase ntawm E. cuniculi ribosome muaj cov qauv zoo ib yam li lwm cov eukaryotic ribosomes (Fig. 1d), qhov chaw txiav txim siab txawv vim qhov sib txawv ntawm nucleotide 1491 (E. coli numbering, Fig. 1e, f).Qhov kev soj ntsuam no yog qhov tseem ceeb vim tias qhov chaw txiav txim siab ntawm eukaryotic ribosomes feem ntau muaj cov seem G1408 thiab A1491 piv rau cov kab mob-hom residues A1408 thiab G1491.Qhov kev hloov pauv no qhia txog qhov sib txawv ntawm cov kab mob thiab cov kab mob eukaryotic ribosomes rau cov tsev neeg aminoglycoside ntawm cov tshuaj tua kab mob ribosomal thiab lwm cov molecules me me uas tsom rau qhov chaw txiav txim siab.Ntawm qhov chaw txiav txim siab ntawm E. cuniculi ribosome, residue A1491 tau hloov nrog U1491, muaj peev xwm tsim kom muaj qhov sib txuas tshwj xeeb rau cov me me molecules tsom rau qhov chaw nquag no.Tib yam A14901 variant kuj muaj nyob rau hauv lwm cov microsporidia xws li P. locustae thiab V. necatrix, qhia tias nws yog dav ntawm microsporidia hom (Fig. 1f).
Vim tias peb cov qauv E. cuniculi ribosome raug cais tawm ntawm cov kab mob metabolically tsis ua haujlwm, peb tau sim daim ntawv qhia cryo-EM ntawm E. cuniculi rau yav dhau los piav txog ribosome khi nyob rau hauv kev ntxhov siab lossis kev tshaib plab.Cov yam ntxwv hibernation 31,32,36,37,38. Peb sib phim cov qauv tsim yav dhau los ntawm hibernating ribosome nrog rau daim ntawv qhia cryo-EM ntawm E. cuniculi ribosome.Rau docking, S. cerevisiae ribosomes tau siv nyob rau hauv complex nrog hibernation factor Stm138, locust ribosomes nyob rau hauv complex nrog Lso232 factor, thiab V. necatrix ribosomes nyob rau hauv complex nrog Mdf1 thiab Mdf231 yam.Nyob rau tib lub sijhawm, peb pom qhov ceev ntawm cryo-EM sib haum rau cov khoom seem Mdf1.Zoo ib yam li Mdf1 khi rau V. necatrix ribosome, Mdf1 kuj khi rau E. cuniculi ribosome, qhov uas nws thaiv E site ntawm ribosome, tejzaum nws pab ua kom ribosomes muaj thaum cov kab mob parasites ua metabolically tsis ua haujlwm thaum lub cev tsis ua haujlwm (Daim duab 2).).
Mdf1 thaiv E qhov chaw ntawm ribosome, uas zoo nkaus li pab ua kom tsis muaj zog ntawm ribosome thaum cov kab mob cab ua rau metabolically tsis ua haujlwm.Hauv cov qauv ntawm E. cuniculi ribosome, peb pom tias Mdf1 ua ib qho kev sib cuag yav dhau los tsis paub nrog L1 ribosome qia, ib feem ntawm ribosome uas pab txhawb kev tso tawm deacylated tRNA los ntawm ribosome thaum lub sij hawm protein synthesis.Cov neeg sib tham no qhia tias Mdf1 dissociates los ntawm ribosome siv tib lub tswv yim zoo li deacetylated tRNA, muab cov lus piav qhia txog yuav ua li cas cov ribosome tshem tawm Mdf1 kom rov ua cov protein synthesis.
Txawm li cas los xij, peb cov qauv qhia qhov tsis paub txog kev sib cuag ntawm Mdf1 thiab L1 ribosome ceg (ib feem ntawm ribosome uas pab tso tawm deacylated tRNA los ntawm ribosome thaum lub sij hawm tsim cov protein).Tshwj xeeb, Mdf1 siv tib cov kev sib cuag raws li lub luj tshib ntu ntawm deacylated tRNA molecule (Fig. 2).Qhov no yav dhau los tsis paub txog cov qauv molecular tau pom tias Mdf1 dissociates los ntawm ribosome siv tib lub tswv yim zoo li deacetylated tRNA, uas piav qhia txog yuav ua li cas lub ribosome tshem tawm qhov hibernation yam tseem ceeb los rov ua cov protein synthesis.
Thaum tsim cov qauv rRNA, peb pom tias E. cuniculi ribosome tau folded rRNA txawv txav, uas peb hu ua fused rRNA (Fig. 3).Nyob rau hauv ribosomes uas nthuav peb lub neej, rRNA folds rau hauv cov qauv uas feem ntau rRNA bases ob lub hauv paus khub thiab quav nrog ib leeg lossis cuam tshuam nrog ribosomal proteins38,39,40.Txawm li cas los xij, hauv E. cuniculi ribosomes, rRNAs zoo li ua txhaum txoj cai folding no los ntawm kev hloov qee qhov ntawm lawv cov helices rau hauv thaj tsam rRNA unfolded.
Cov qauv ntawm H18 25S rRNA helix hauv S. cerevisiae, V. necatrix, thiab E. cuniculi.Feem ntau, hauv ribosomes hla peb lub neej, qhov txuas txuas txuas mus rau hauv RNA helix uas muaj 24 txog 34 residues.Hauv Microsporidia, qhov sib txawv, qhov rRNA linker no maj mam txo mus rau ob qho tib si-stranded uridine-nplua nuj linkers uas tsuas muaj 12 residues.Feem ntau ntawm cov residues yog raug rau cov kuab tshuaj.Daim duab qhia tau hais tias parasitic microsporidia tshwm sim ua txhaum txoj cai dav dav ntawm rRNA folding, qhov twg rRNA bases feem ntau yog ua ke rau lwm lub hauv paus lossis koom nrog rRNA-protein kev sib cuam tshuam.Hauv microsporidia, qee qhov rRNA fragments coj mus rau qhov tsis zoo, uas yav dhau los rRNA helix dhau los ua ib feem ntawm ib qho elongated yuav luag nyob rau hauv txoj kab ncaj nraim.Lub xub ntiag ntawm cov cheeb tsam txawv txawv no tso cai rau microsporidia rRNA los khi cov rRNA nyob deb ntawm cov khoom siv tsawg tsawg ntawm RNA hauv paus.
Qhov piv txwv zoo tshaj plaws ntawm qhov kev hloov pauv hloov pauv no tuaj yeem pom hauv H18 25S rRNA helix (Fig. 3).Hauv hom E. coli rau tib neeg, lub hauv paus ntawm rRNA helix no muaj 24-32 nucleotides, tsim cov helix me ntsis.Nyob rau hauv yav tas los txheeb xyuas ribosomal qauv los ntawm V. necatrix thiab P. locustae, 31,32 lub hauv paus ntawm H18 helix yog ib feem uncoiled, tab sis nucleotide puag pairing yog khaws cia.Txawm li cas los xij, hauv E. cuniculi no rRNA fragment dhau los ua qhov luv tshaj linkers 228UUUGU232 thiab 301UUUUUUUUU307.Tsis zoo li cov rRNA feem ntau, cov uridine-nplua nuj linkers no tsis coil los yog ua rau muaj kev sib cuag nrog ribosomal proteins.Hloov chaw, lawv txais cov kuab tshuaj-qhib thiab nthuav dav cov qauv uas cov rRNA strands txuas ntxiv yuav luag ncaj.Qhov no stretched conformation piav qhia yuav ua li cas E. cuniculi siv tsuas yog 12 RNA hauv paus los ua kom tiav 33 Å qhov sib txawv ntawm H16 thiab H18 rRNA helices, thaum lwm hom tsiaj yuav tsum muaj tsawg kawg yog ob zaug ntau li ntau rRNA hauv paus los sau qhov sib txawv.
Yog li, peb tuaj yeem ua kom pom tau tias, dhau los ntawm kev sib zog ua kom tsis zoo, cov kab mob parasitic microsporidia tau tsim lub tswv yim los cog lus txawm tias cov rRNA ntu uas tseem khaws cia dav dav thoob plaws hauv peb lub neej.Pom tau tias, los ntawm kev sib txuas cov kev hloov pauv uas hloov rRNA helices rau hauv luv luv poly-U txuas, E. cuniculi tuaj yeem tsim cov rRNA txawv txav uas muaj ob peb nucleotides li ua tau rau ligation ntawm distal rRNA fragments.Qhov no pab piav qhia yuav ua li cas microsporidia ua tiav qhov txo qis hauv lawv cov qauv molecular yam tsis tau poob lawv cov qauv thiab kev ua haujlwm zoo.
Lwm qhov txawv txav ntawm E. cuniculi rRNA yog qhov tsos ntawm rRNA tsis muaj thickenings (Fig. 4).Bulges yog nucleotides tsis muaj lub hauv paus khub uas twist tawm ntawm RNA helix es tsis txhob nkaum hauv nws.Feem ntau rRNA protrusions ua raws li molecular adhesives, pab khi ribosomal proteins uas nyob ib sab los yog lwm yam rRNA fragments.Qee qhov bulges ua raws li pob khawm, tso cai rau rRNA helix kom flex thiab quav zoo rau kev tsim cov protein synthesis 41 .
Ib qho rRNA protrusion (S. cerevisiae numbering) yog tsis tuaj ntawm E. cuniculi ribosome qauv, tab sis tam sim no nyob rau hauv feem ntau lwm yam eukaryotes b E. coli, S. cerevisiae, H. sapiens, thiab E. cuniculi internal ribosomes.cov kab mob tsis muaj ntau yam ntawm cov qub qub, kev txuag rRNA bulges.Cov thickenings stabilize cov qauv ribosome;Yog li ntawd, lawv qhov tsis muaj nyob hauv microsporidia qhia tau tias txo qis kev ruaj ntseg ntawm rRNA folding hauv microsporidia parasites.Kev sib piv nrog P stems (L7 / L12 stems nyob rau hauv cov kab mob) qhia tau hais tias qhov poob ntawm rRNA pob tej zaum kuj coincides nrog cov tsos ntawm tshiab pob nyob rau hauv ib sab ntawm cov poob pob.Lub H42 helix nyob rau hauv 23S/28S rRNA muaj cov pob txha thaum ub (U1206 hauv Saccharomyces cerevisiae) kwv yees tias muaj tsawg kawg yog 3.5 billion xyoo vim nws kev tiv thaiv hauv peb lub neej.Nyob rau hauv microsporidia, cov pob no raug tshem tawm.Txawm li cas los xij, ib lub pob txha tshiab tau tshwm sim ntawm ib sab ntawm lub pob ploj (A1306 hauv E. cuniculi).
Strikingly, peb pom tias E. cuniculi ribosomes tsis muaj feem ntau ntawm rRNA bulges pom nyob rau hauv lwm hom, nrog rau ntau tshaj 30 bulges khaws cia nyob rau hauv lwm yam eukaryotes (Fig. 4a).Qhov kev poob no tshem tawm ntau qhov sib cuag ntawm ribosomal subunits thiab rRNA helices nyob ib sab, qee zaum tsim cov khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoob khoobQhov tseem ceeb, peb pom tias feem ntau ntawm cov bulges no kuj tau ploj mus rau yav dhau los tau txheeb xyuas V. necatrix thiab P. locustae ribosome cov qauv, uas tau saib dhau los ntawm cov qauv kev soj ntsuam yav dhau los31,32.
Qee lub sij hawm qhov poob ntawm rRNA bulges yog nrog los ntawm kev txhim kho ntawm cov bulges tshiab ntawm ib sab ntawm lub pob ploj.Piv txwv li, ribosomal P-stem muaj U1208 bulge (hauv Saccharomyces cerevisiae) uas muaj sia nyob los ntawm E. coli rau tib neeg thiab yog li kwv yees li 3.5 billion xyoo.Thaum lub sij hawm sib txuas ntawm cov protein, cov pob no pab P qia txav ntawm qhov qhib thiab kaw kom cov ribosome tuaj yeem nrhiav cov ntsiab lus txhais lus thiab xa lawv mus rau qhov chaw nquag.Hauv E. cuniculi ribosomes, qhov thickening no tsis tuaj;Txawm li cas los xij, ib qho tshiab thickening (G883) tsuas yog nyob rau hauv peb lub hauv paus khub tuaj yeem pab txhawb kev kho kom zoo dua qub ntawm P qia (Fig. 4c).
Peb cov ntaub ntawv ntawm rRNA tsis muaj bulges qhia tias rRNA kev txo qis tsis txwv rau qhov poob ntawm rRNA ntsiab lus ntawm qhov chaw ntawm ribosome, tab sis kuj tseem tuaj yeem koom nrog ribosome nucleus, tsim kom muaj cov kab mob tshwj xeeb molecular uas tsis tau piav qhia hauv cov hlwb dawb.cov tsiaj nyob yog pom.
Tom qab ua qauv canonical ribosomal proteins thiab rRNA, peb pom tias cov pa ribosomal Cheebtsam tsis tuaj yeem piav qhia peb feem ntawm daim duab cryo-EM.Ob tug ntawm cov fragments no yog me me molecules (Fig. 5, Supplementary Fig. 8).Thawj ntu yog sandwiched ntawm ribosomal proteins uL15 thiab eL18 nyob rau hauv ib txoj hauj lwm feem ntau nyob ntawm C-terminus ntawm eL18, uas yog luv luv hauv E. cuniculi.Txawm hais tias peb tsis tuaj yeem txiav txim siab tus kheej ntawm cov molecule no, qhov loj thiab cov duab ntawm cov kob ntom ntom no tau piav qhia zoo los ntawm qhov muaj cov spermidine molecules.Nws txoj kev khi rau ribosome yog ruaj khov los ntawm microsporidia-kev hloov pauv tshwj xeeb hauv uL15 cov proteins (Asp51 thiab Arg56), uas zoo li ua kom muaj kev sib raug zoo ntawm ribosome rau cov molecule me me, vim lawv tso cai rau uL15 los qhwv cov molecule me rau hauv cov qauv ribosomal.Daim duab ntxiv 2).8, cov ntaub ntawv ntxiv 1, 2).
Cryo-EM daim duab qhia pom muaj cov nucleotides sab nraum lub ribose khi rau E. cuniculi ribosome.Hauv E. cuniculi ribosome, cov nucleotide no nyob tib qhov chaw li 25S rRNA A3186 nucleotide (Saccharomyces cerevisiae numbering) nyob rau hauv feem ntau lwm cov eukaryotic ribosomes.b Nyob rau hauv lub ribosomal qauv ntawm E. cuniculi, no nucleotide nyob nruab nrab ntawm cov ribosomal proteins uL9 thiab eL20, yog li stabilizing kev sib cuag ntawm ob proteins.cd eL20 kev txuag kev tsom xam ntawm cov kab mob microsporidia.Cov ntoo phylogenetic ntawm Microsporidia hom (c) thiab ntau qhov sib txuas ua ke ntawm eL20 protein (d) qhia tias nucleotide-binding residues F170 thiab K172 tau khaws cia hauv feem ntau ntawm Microsporidia, tshwj tsis yog S. lophii, tshwj tsis yog thaum ntxov branching Microsporidia, uas khaws cia L9.e Daim duab no qhia tau hais tias nucleotide-binding residues F170 thiab K172 tsuas yog muaj nyob rau hauv eL20 ntawm cov microsporidia genome uas txo qis heev, tab sis tsis nyob hauv lwm cov eukaryotes.Zuag qhia tag nrho, cov ntaub ntawv no qhia tias Microsporidian ribosomes tau tsim ib qhov chaw sib txuas nucleotide uas zoo li khi AMP molecules thiab siv lawv los tswj cov protein-protein kev sib cuam tshuam hauv cov qauv ribosomal.Kev txuag siab ntawm qhov chaw sib khi no hauv Microsporidia thiab nws qhov tsis muaj nyob hauv lwm cov eukaryotes qhia tias qhov chaw no tuaj yeem muab kev xaiv ciaj sia zoo rau Microsporidia.Yog li, lub hnab tshos nucleotide-binding nyob rau hauv microsporidia ribosome tsis tshwm sim los yog degenerate feature los yog kawg daim ntawv ntawm rRNA degradation raws li tau piav yav tas los, tab sis yog ib tug muaj txiaj ntsim evolutionary innovation uas tso cai rau lub microsporidia ribosome ncaj qha mus khi me me molecules, siv lawv li molecular tsev blocks.tsim blocks rau ribosomes.Qhov kev tshawb pom no ua rau microsporidia ribosome tsuas yog ribosome paub siv ib zaug xwb nucleotide ua nws lub tsev thaiv.f Hypothetical evolutionary txoj kev muab los ntawm nucleotide khi.
Qhov thib ob uas tsis muaj molecular hnyav ntom yog nyob ntawm qhov sib txuas ntawm ribosomal proteins uL9 thiab eL30 (Fig. 5a).Qhov kev sib txuas no tau piav qhia yav dhau los hauv cov qauv ntawm Saccharomyces cerevisiae ribosome ua qhov chaw khi rau 25S nucleotide ntawm rRNA A3186 (ib feem ntawm ES39L rRNA txuas ntxiv) 38.Nws tau pom tias nyob rau hauv degenerate P. locustae ES39L ribosomes, qhov kev sib txuas no khi ib qho tsis paub txog nucleotide 31, thiab nws tau xav tias qhov nucleotide no yog qhov txo qis kawg ntawm rRNA, uas qhov ntev ntawm rRNA yog ~ 130-230 hauv paus.ES39L raug txo rau ib leeg nucleotide 32.43.Peb cov duab cryo-EM txhawb lub tswv yim tias qhov ceev tuaj yeem piav qhia los ntawm nucleotides.Txawm li cas los xij, qhov kev daws teeb meem siab dua ntawm peb cov qauv pom tau tias cov nucleotide no yog ib qho molecule extraribosomal, tej zaum AMP (Fig. 5a, b).
Tom qab ntawd peb nug seb qhov chaw sib txuas nucleotide puas tshwm sim hauv E. cuniculi ribosome lossis seb nws puas muaj yav dhau los.Txij li thaum nucleotide khi feem ntau yog kho los ntawm Phe170 thiab Lys172 residues hauv eL30 ribosomal protein, peb tau soj ntsuam kev txuag ntawm cov residues hauv 4396 tus neeg sawv cev eukaryotes.Raws li nyob rau hauv cov ntaub ntawv ntawm uL15 saum toj no, peb pom tias Phe170 thiab Lys172 residues yog heev conserved tsuas yog nyob rau hauv ib txwm Microsporidia, tab sis nyob rau hauv lwm yam eukaryotes, nrog rau atypical Microsporidia Mitosporidium thiab Amphiamblys, nyob rau hauv uas lub ES39L rRNA fragment yog tsis txo (4.5g 4.5).-e).
Ua ke, cov ntaub ntawv no txhawb nqa lub tswv yim tias E. cuniculi thiab tejzaum nws muaj lwm yam canonical microsporidia tau hloov zuj zus lub peev xwm los ua kom tau txais txiaj ntsig zoo ntawm cov metabolites me me hauv cov qauv ribosome los them rau qhov poob ntawm rRNA thiab cov protein ntau.Hauv kev ua li ntawd, lawv tau tsim lub peev xwm tshwj xeeb los khi nucleotides sab nraum lub ribosome, qhia tias cov kab mob cab molecular them nyiaj los ntawm kev ntes cov metabolites me me thiab siv lawv ua cov qauv ua qauv ntawm degraded RNA thiab cov khoom tawg..
Qhov thib peb unsimulated ib feem ntawm peb daim ntawv qhia cryo-EM, pom nyob rau hauv lub loj ribosomal subunit.Qhov kev daws teeb meem siab heev (2.6 Å) ntawm peb daim ntawv qhia qhia tias qhov ntom ntom no yog cov proteins uas muaj kev sib txuas tshwj xeeb ntawm cov saw loj loj, uas tso cai rau peb txheeb xyuas qhov ntom ntom no raws li cov protein uas tsis tau paub txog ribosomal uas peb tau txheeb xyuas tias nws muaj npe msL2 (Microsporidia-cov protein tshwj xeeb L2) (txoj kev, daim duab 6).Peb qhov kev tshawb fawb homology tau pom tias msL2 tau khaws cia hauv Microsporidia clade ntawm genus Encephaliter thiab Orosporidium, tab sis tsis tuaj yeem nyob hauv lwm hom, suav nrog lwm yam Microsporidia.Hauv cov qauv ribosomal, msL2 nyob hauv qhov sib txawv tsim los ntawm kev poob ntawm qhov txuas ntxiv ES31L rRNA.Hauv qhov khoob no, msL2 pab kom ruaj khov rRNA folding thiab tuaj yeem them nyiaj rau qhov poob ntawm ES31L (Daim duab 6).
Electron ceev thiab qauv ntawm Microsporidia-specific ribosomal protein msL2 pom nyob rau hauv E. cuniculi ribosomes.b Feem ntau cov eukaryotic ribosomes, suav nrog 80S ribosome ntawm Saccharomyces cerevisiae, muaj ES19L rRNA amplification poob hauv feem ntau hom Microsporidian.Cov qauv tsim yav dhau los ntawm V. necatrix microsporidia ribosome qhia tias qhov poob ntawm ES19L hauv cov kab mob no tau them nyiaj los ntawm kev hloov pauv ntawm msL1 ribosomal protein tshiab.Hauv txoj kev tshawb no, peb pom tias E. cuniculi ribosome kuj tsim ib qho ntxiv ribosomal RNA mimic protein raws li qhov pom tseeb them nyiaj rau qhov poob ntawm ES19L.Txawm li cas los xij, msL2 (tam sim no annotated raws li qhov hypothetical ECU06_1135 protein) thiab msL1 muaj ntau yam qauv thiab evolutionary keeb kwm.c Qhov kev tshawb pom no ntawm cov tiam ntawm evolutionarily unrelated msL1 thiab msL2 ribosomal proteins qhia tau hais tias yog ribosomes accumulate detrimental mutations nyob rau hauv lawv rRNA, lawv muaj peev xwm ua tau unprecedented theem ntawm compositional ntau haiv neeg nyob rau hauv txawm ib tug me me subset ntawm ze ze cov tsiaj.Qhov kev tshawb pom no tuaj yeem pab qhia meej txog keeb kwm thiab kev hloov pauv ntawm mitochondrial ribosome, uas paub txog nws qhov txo qis rRNA thiab txawv txav txawv txav ntawm cov protein nyob hauv ntau hom.
Peb mam li muab piv rau msL2 protein nrog rau yav tas los piav msL1 protein, tib lub npe hu ua microsporidia-specific ribosomal protein nyob rau hauv V. necatrix ribosome.Peb xav sim seb msL1 thiab msL2 puas cuam tshuam txog kev hloov pauv.Peb qhov kev soj ntsuam tau pom tias msL1 thiab msL2 nyob hauv tib lub kab noj hniav hauv cov qauv ribosomal, tab sis muaj cov qauv sib txawv ntawm cov thawj thiab qib theem, uas qhia tias lawv muaj kev ywj pheej evolutionary keeb kwm (Fig. 6).Yog li, peb qhov kev tshawb pom ntawm msL2 muab pov thawj tias cov pab pawg ntawm cov kab mob eukaryotic tuaj yeem ua rau nws tus kheej hloov pauv cov txheej txheem sib txawv ntawm cov ribosomal proteins los them rau qhov poob ntawm rRNA fragments.Qhov kev tshawb pom no yog qhov tseem ceeb hauv qhov feem ntau cytoplasmic eukaryotic ribosomes muaj cov protein tsis sib xws, suav nrog tib tsev neeg ntawm 81 ribosomal proteins.Qhov tshwm sim ntawm msL1 thiab msL2 nyob rau hauv ntau lub clades ntawm microsporidia nyob rau hauv teb rau qhov poob ntawm ncua rRNA ntu qhia tias degradation ntawm parasite's molecular architecture ua rau cab mus nrhiav kev hloov pauv, uas thaum kawg yuav ua rau lawv tau txais nyob rau hauv cov kab mob sib txawv.cov qauv.
Thaum kawg, thaum peb tus qauv ua tiav, peb muab piv rau cov khoom xyaw ntawm E. cuniculi ribosome nrog qhov uas tau kwv yees los ntawm genome ib ntus.Ob peb ribosomal proteins, suav nrog eL14, eL38, eL41, thiab eS30, yav tas los xav tias yuav ploj los ntawm E. cuniculi genome vim qhov tsis pom tseeb ntawm lawv cov homologues los ntawm E. cuniculi genome.Kev poob ntawm ntau cov ribosomal proteins kuj tau kwv yees nyob rau hauv feem ntau lwm cov kab mob uas txo qis hauv lub cev thiab endosymbionts.Piv txwv li, txawm hais tias feem ntau cov kab mob nyob dawb muaj tib tsev neeg ntawm 54 ribosomal proteins, tsuas yog 11 ntawm cov tsev neeg cov protein no tau kuaj pom cov homologues hauv txhua qhov tshuaj ntsuam genome ntawm tus tswv tsev txwv cov kab mob.Hauv kev txhawb nqa ntawm qhov kev xav no, kev poob ntawm ribosomal proteins tau raug sim nyob rau hauv V. necatrix thiab P. locustae microsporidia, uas tsis muaj eL38 thiab eL4131,32 proteins.
Txawm li cas los xij, peb cov qauv qhia tias tsuas yog eL38, eL41, thiab eS30 tiag tiag tau ploj hauv E. cuniculi ribosome.Cov protein eL14 tau khaws cia thiab peb cov qauv qhia tias vim li cas cov protein no tsis tuaj yeem pom hauv kev tshawb nrhiav homology (Fig. 7).Hauv E. cuniculi ribosomes, feem ntau ntawm eL14 khi qhov chaw yog ploj vim degradation ntawm rRNA-amplified ES39L.Thaum tsis muaj ES39L, eL14 poob feem ntau ntawm nws cov qauv thib ob, thiab tsuas yog 18% ntawm eL14 ib ntus tau zoo ib yam hauv E. cuniculi thiab S. cerevisiae.Qhov kev khaws cia tsis zoo no yog qhov zoo tshaj plaws vim tias txawm tias Saccharomyces cerevisiae thiab Homo sapiens-cov kab mob uas hloov zuj zus mus txog 1.5 billion xyoo sib nrug-sib faib ntau dua 51% ntawm tib qhov seem hauv eL14.Qhov kev poob qis ntawm kev txuag no piav qhia vim li cas E. cuniculi eL14 tam sim no tau sau tseg tias yog cov protein ntau M970_061160 thiab tsis yog eL1427 ribosomal protein.
thiab Microsporidia ribosome poob ES39L rRNA txuas ntxiv, uas tau tshem tawm ib nrab ntawm eL14 ribosomal protein khi qhov chaw.Thaum tsis muaj ES39L, eL14 microspore protein ua rau poob ntawm cov qauv thib ob, uas yav dhau los rRNA-binding α-helix degenerates rau hauv lub voj me me.b Ntau qhov kev sib txuas ua ke qhia tau hais tias eL14 cov protein ntau tau txais txiaj ntsig zoo hauv eukaryotic hom (57% kab ke tus kheej ntawm cov poov xab thiab tib neeg homologues), tab sis kev txuag tsis zoo thiab sib txawv hauv microsporidia (uas tsis pub ntau tshaj 24% ntawm cov residues zoo ib yam rau eL14 homologue).los ntawm S. cerevisiae los yog H. sapiens).Qhov kev txuag tsis zoo no thiab cov qauv kev hloov pauv thib ob piav qhia tias vim li cas eL14 homologue tsis tau pom hauv E. cuniculi thiab vim li cas cov protein no xav tias tau ploj hauv E. cuniculi.Nyob rau hauv sib piv, E. cuniculi eL14 yav tas los annotated raws li ib tug putative M970_061160 protein.Qhov kev soj ntsuam no qhia tias microsporidia genome muaj ntau haiv neeg tam sim no overestimated: qee cov noob tam sim no xav tias ploj hauv microsporidia yog qhov tseeb khaws cia, txawm tias nyob rau hauv cov ntaub ntawv sib txawv heev;es tsis txhob, ib txhia xav kom code rau microsporidia noob rau worm-specific proteins (piv txwv li, cov hypothetical protein M970_061160) ua tau code rau cov proteins uas muaj ntau haiv neeg pom nyob rau hauv lwm yam eukaryotes.
Qhov kev tshawb pom no qhia tau hais tias rRNA denaturation tuaj yeem ua rau kev poob qis ntawm kev txuag kev sib txuas hauv cov kab mob ribosomal uas nyob ib sab, ua rau cov proteins no tsis tuaj yeem tshawb nrhiav homology.Yog li, peb yuav overestimate qhov tseeb ntawm molecular degradation nyob rau hauv me me genome kab mob, txij li thaum qee cov proteins xav tias yuav ploj mus, txawm tias nyob rau hauv cov ntaub ntawv hloov siab heev.
Yuav ua li cas cov kab mob tuaj yeem khaws cov haujlwm ntawm lawv cov tshuab molecular nyob rau hauv cov xwm txheej ntawm kev txo qis genome?Peb txoj kev tshawb fawb teb cov lus nug no los ntawm kev piav qhia txog cov qauv molecular complex (ribosome) ntawm E. cuniculi, ib yam kab mob nrog ib qho ntawm cov genomes eukaryotic tsawg tshaj plaws.
Nws tau paub txog yuav luag ob xyoo lawm tias cov protein thiab RNA molecules nyob rau hauv cov kab mob microbial feem ntau txawv ntawm lawv cov homologous molecules hauv cov tsiaj muaj sia nyob vim lawv tsis muaj cov chaw tswj xyuas zoo, raug txo mus rau 50% ntawm lawv qhov loj me hauv cov microbes dawb, thiab lwm yam.Muaj ntau yam kev hloov pauv uas cuam tshuam folding thiab ua haujlwm.Piv txwv li, ribosomes ntawm cov kab mob me me, suav nrog ntau cov kab mob hauv lub cev thiab cov kab mob endosymbionts, xav tias yuav tsis muaj ob peb ribosomal proteins thiab txog li ib feem peb ntawm rRNA nucleotides piv rau cov tsiaj muaj sia nyob dawb 27, 29, 30, 49. Txawm li cas los xij, txoj hauv kev cov kab mob no tseem nyob hauv cov kab mob loj.
Peb txoj kev tshawb fawb qhia tau hais tias cov qauv ntawm macromolecules tuaj yeem nthuav tawm ntau yam ntawm cov evolution uas nyuaj rau rho tawm los ntawm kev sib piv cov kev tshawb fawb genomic ntawm cov kab mob intracellular thiab lwm yam kab mob uas txwv tsis pub muaj tus tswv tsev (Supplementary Fig. 7).Piv txwv li, piv txwv ntawm eL14 protein qhia tau hais tias peb muaj peev xwm overestimate qhov tseeb degree ntawm degradation ntawm molecular apparatus nyob rau hauv parasitic hom.Cov kab mob Encephalitic tam sim no ntseeg tau tias muaj ntau pua tus kab mob microsporidia tshwj xeeb.Txawm li cas los xij, peb cov txiaj ntsig tau pom tias qee qhov zoo li cov noob tshwj xeeb yog qhov sib txawv ntawm cov noob uas muaj nyob hauv lwm cov eukaryotes.Tsis tas li ntawd, piv txwv ntawm msL2 protein qhia tau hais tias peb saib xyuas cov ribosomal proteins tshiab thiab saib xyuas cov ntsiab lus ntawm cov kab mob cab molecular.Qhov piv txwv ntawm cov molecules me me qhia tau hais tias peb tuaj yeem saib xyuas qhov kev tsim kho tshiab tshaj plaws hauv cov kab mob parasitic molecular uas tuaj yeem ua rau lawv ua haujlwm lom neeg tshiab.
Ua ke, cov txiaj ntsig no txhim kho peb txoj kev nkag siab ntawm qhov sib txawv ntawm cov qauv molecular ntawm tus tswv tsev txwv cov kab mob thiab lawv cov koom nrog hauv cov kab mob uas muaj sia nyob.Peb qhia tau hais tias cov tshuab molecular, xav ntev kom txo qis, degenerate, thiab raug rau ntau yam kev hloov pauv tsis zoo, es tsis txhob muaj cov txheej txheem ntawm kev saib xyuas cov yam ntxwv txawv txawv.
Ntawm qhov tod tes, cov tsis-loj rRNA fragments thiab fused fragments uas peb pom nyob rau hauv lub ribosomes ntawm E. cuniculi qhia tias genome txo yuav hloov tau txawm tias cov seem ntawm lub hauv paus molecular machinery uas tau khaws cia nyob rau hauv peb lub neej - tom qab yuav luag 3.5 billion xyoo.ywj siab evolution ntawm hom.
Cov bulge-free thiab fused rRNA fragments nyob rau hauv E. cuniculi ribosomes yog tshwj xeeb yog txaus siab rau lub teeb ntawm yav dhau los kev tshawb fawb ntawm RNA molecules nyob rau hauv endosymbiotic kab mob.Piv txwv li, hauv aphid endosymbiont Buchnera aphidicola, rRNA thiab tRNA molecules tau pom tias muaj cov qauv kub-rhiab heev vim A + T muaj pes tsawg leeg tsis zoo thiab feem ntau ntawm cov tsis-canonical puag khub 20,50.Cov kev hloov pauv no hauv RNA, nrog rau cov kev hloov pauv hauv cov protein molecules, tam sim no xav tias yog lub luag haujlwm rau kev ywj pheej ntawm endosymbionts ntawm cov neeg koom tes thiab qhov tsis muaj peev xwm ntawm endosymbionts hloov cov cua sov 21, 23.Txawm hais tias parasitic microsporidia rRNA muaj cov kev hloov pauv txawv, qhov xwm txheej ntawm cov kev hloov pauv no qhia tias txo qis thermal stability thiab ntau dua kev vam khom ntawm chaperone proteins yuav yog cov yam ntxwv ntawm RNA molecules hauv cov kab mob uas txo cov genomes.
Ntawm qhov tod tes, peb cov qauv qhia tau hais tias parasite microsporidia tau hloov kho lub peev xwm tshwj xeeb los tiv thaiv dav dav rRNA thiab cov khoom tawg ntawm cov protein, txhim kho lub peev xwm los siv ntau thiab yooj yim muaj cov metabolites me me raws li cov qauv qauv ntawm degenerate rRNA thiab cov khoom tawg.Molecular qauv degradation..Qhov kev xav no tau txais kev txhawb nqa los ntawm qhov tseeb tias cov molecules me me uas them rau qhov poob ntawm cov khoom tawg ntawm cov protein nyob hauv rRNA thiab ribosomes ntawm E. cuniculi khi rau microsporidia-specific residues hauv uL15 thiab eL30 proteins.Qhov no qhia tau hais tias kev khi me me rau ribosomes tej zaum yuav yog cov khoom ntawm kev xaiv zoo, nyob rau hauv uas Microsporidia-kev hloov pauv tshwj xeeb hauv ribosomal proteins tau raug xaiv rau lawv lub peev xwm los ua kom muaj kev sib raug zoo ntawm ribosomes rau cov khoom me me, uas tuaj yeem ua rau cov kab mob ribosomal zoo dua.Qhov kev tshawb pom nthuav tawm qhov kev hloov tshiab tshiab hauv cov qauv molecular ntawm cov kab mob microbial thiab ua rau peb nkag siab zoo dua li cas cov kab mob cab molecular tswj lawv txoj haujlwm txawm tias txo qis kev hloov pauv.
Tam sim no, kev txheeb xyuas ntawm cov me me molecules tseem tsis meej.Nws tsis paub meej yog vim li cas cov tsos ntawm cov me me molecules nyob rau hauv lub ribosomal qauv txawv ntawm microsporidia hom.Tshwj xeeb, nws tsis paub meej tias vim li cas nucleotide khi tau pom nyob rau hauv ribosomes ntawm E. cuniculi thiab P. locustae, thiab tsis nyob hauv ribosomes ntawm V. necatrix, txawm tias muaj F170 residue hauv eL20 thiab K172 proteins ntawm V. necatrix.Qhov kev tshem tawm no yuav tshwm sim los ntawm residue 43 uL6 (nyob ib sab ntawm lub hnab tshos nucleotide khi), uas yog tyrosine hauv V. necatrix thiab tsis yog threonine hauv E. cuniculi thiab P. locustae.Cov khoom loj uas muaj ntxhiab tsw qab ntawm Tyr43 tuaj yeem cuam tshuam nrog nucleotide khi vim muaj kev sib tshooj steric.Xwb, qhov pom meej nucleotide deletion tej zaum yuav yog vim qhov kev daws teeb meem tsawg ntawm cryo-EM imaging, uas cuam tshuam cov qauv ntawm V. necatrix ribosomal fragments.
Ntawm qhov tod tes, peb txoj haujlwm qhia tias cov txheej txheem ntawm genome decay tej zaum yuav yog ib qho kev tsim muaj zog.Hauv particular, cov qauv ntawm E. cuniculi ribosome qhia tias qhov poob ntawm rRNA thiab cov khoom tawg ntawm cov protein nyob rau hauv microsporidia ribosome tsim evolutionary siab uas txhawb kev hloov hauv ribosome qauv.Cov kev hloov pauv no tshwm sim deb ntawm qhov chaw nquag ntawm ribosome thiab tshwm sim los pab tswj (lossis rov qab) kev pom zoo ribosome sib dhos uas yuav txwv tsis pub cuam tshuam los ntawm kev txo qis rRNA.Qhov no qhia tau hais tias ib qho kev hloov tshiab loj ntawm microsporidia ribosome zoo li tau hloov zuj zus mus rau qhov xav tau kom tsis txhob gene drift.
Tej zaum qhov no yog qhov zoo tshaj plaws piav qhia los ntawm nucleotide khi, uas tsis tau pom nyob rau hauv lwm yam kab mob kom deb li deb.Qhov tseeb hais tias nucleotide-binding residues muaj nyob rau hauv ib txwm microsporidia, tab sis tsis yog nyob rau hauv lwm yam eukaryotes, qhia hais tias nucleotide-binding qhov chaw tsis yog tsuas yog relics tos ploj, los yog qhov chaw kawg rau rRNA yuav tsum tau rov qab mus rau hauv daim ntawv ntawm ib tug nucleotides.Hloov chaw, lub vev xaib no zoo li qhov muaj txiaj ntsig zoo uas tuaj yeem hloov pauv ntau qhov kev xaiv zoo.Nucleotide binding sites tej zaum yuav yog ib qho khoom los ntawm kev xaiv ntuj: ib zaug ES39L degraded, microsporidia raug yuam kom nrhiav nyiaj them rov qab zoo ribosome biogenesis thaum tsis muaj ES39L.Txij li cov nucleotide no tuaj yeem ua raws li cov kev sib txuas ntawm cov molecular ntawm A3186 nucleotide hauv ES39L, cov nucleotide molecule dhau los ua ib lub tsev thaiv ntawm ribosome, qhov kev sib txuas ntawm kev sib txuas tau zoo dua los ntawm kev hloov ntawm eL30 ib ntus.
Hais txog kev hloov pauv ntawm molecular ntawm cov kab mob hauv lub cev, peb txoj kev tshawb fawb qhia tau hais tias lub zog ntawm Darwinian natural selection thiab genetic drift ntawm genome decay tsis ua hauj lwm nyob rau hauv parallel, tab sis oscillate.Ua ntej, genetic drift tshem tawm cov yam ntxwv tseem ceeb ntawm biomolecules, ua rau kev mob hnyav.Tsuas yog thaum cov kab mob ua kom tau raws li qhov xav tau los ntawm Darwinian kev xaiv ntuj yuav lawv cov macromolecules muaj lub sijhawm los txhim kho lawv cov kev xav tau zoo tshaj plaws thiab tsim kho tshiab.Qhov tseem ceeb, kev hloov pauv ntawm nucleotide khi qhov chaw hauv E. cuniculi ribosome qhia tias qhov kev poob-rau-tau txais qauv ntawm molecular evolution tsis tsuas yog amortizes deleterious mutations, tab sis qee zaus confers nkaus tshiab zog ntawm parasitic macromolecules.
Lub tswv yim no zoo ib yam nrog Sewell Wright txoj kev txav mus los sib npaug, uas tau hais tias ib qho kev nruj ntawm kev xaiv ntuj txwv tsis pub muaj peev xwm ntawm cov kab mob mus rau innovate51,52,53.Txawm li cas los xij, yog tias cov noob caj noob ces cuam tshuam rau kev xaiv ntuj, cov kev hloov pauv no tuaj yeem tsim cov kev hloov pauv uas tsis nyob hauv lawv tus kheej hloov kho (lossis txawm tias muaj kev puas tsuaj) tab sis ua rau muaj kev hloov pauv ntxiv uas ua rau muaj kev noj qab haus huv ntau dua lossis ua haujlwm lom neeg tshiab.Peb lub moj khaum txhawb lub tswv yim no los ntawm kev piav qhia tias tib hom kev hloov pauv uas txo cov quav thiab kev ua haujlwm ntawm biomolecule zoo li yog lub ntsiab lus tseem ceeb rau nws txoj kev txhim kho.Nyob rau hauv txoj kab nrog kev yeej-yeej evolutionary qauv, peb txoj kev tshawb fawb qhia tau hais tias genome decay, ib txwm saib raws li ib tug degenerative txheej txheem, kuj yog ib tug tseem ceeb tsav tsheb ntawm innovation, tej zaum thiab tej zaum txawm feem ntau cia macromolecules kom tau txais cov kab mob tshiab.tuaj yeem siv lawv.