冠状病毒Coronavirusl论文-1991 Mutational analysis of the RNA pseudoknot component of a coronavirus ribosomal frameshifting signal.pdf

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1、J.Mol.Riol.(1991)220,889-902MutationalAnalysisoftheRNAPseudoknotComponentofaCoronavirusRibosomalFrameshiftingSignalIanBrierleyt,NicolaJ.Rolley,AlisonJ.JennerandStephenC.InglisDivisionofVirologyDepartmentofPathologyUniversityofCambridgeTennisCourtRoad,CambridgeCB2l&P,U.K.(Received12February1991;a

2、ccepted18April1991)ThegenomicRNAofthecoronavirusIBVcontainsanefficientribosomalframeshiftsignalatthejunctionoftheoverlappinglaandlbopenreadingframes.Thesignaliscomprisedoftwoelements,aheptanucleotideslip-siteandadownstreamtertiaryRNAstructureintheformofanRNApseudoknot.Wehaveinvestigatedthestruct

3、ureofthepseudoknotanditscontributiontotheframeshiftprocessbyanalysingtheframeshiftingpropertiesofaseriesofpseudoknotmutants.Ourresultsshowthatthepseudoknotstructurecloselyresemblesthatwhichcanbepredictedfromcurrentbuildingrules,althoughbase-pairformationattheregionwherethetwopseudoknotstemsareth

4、oughttostackco-axiallyisnotapre-requisiteforefficientframeshifting.Thestems,however,mustbeincloseproximitytogenerateafunctionalstructure.Ingeneral,theremovalofasinglebase-paircontactineitherstemissufficienttoreduceorabolishframeshifting.Noprimarysequencedeterminantsinthestemsorloopsappeartobeinv

5、olvedintheframeshiftprocess;aslongastheoverallstiuctureismaintained,frameshiftingishighlyefficient.Thus,smallinsertionsintothepseudoknotloopsandadeletioninloop2thatreduceditslengthtothepredictedfunctionalminimumdidnotinfluenceframeshifting.However,alargeinsertion(467nucleotides)intoloop2abolishe

6、dframeshifting.Asimplestem-loopstructurewithabase-pairedstemofthesamelengthandnucleotidecompositionasthestackedstemsofthepseudoknotcouldnotfunctionallyreplacethepseudoknot,suggestingthatsomeparticularconformationalfeatureofthepseudoknotdeterminesitsabilitytopromoteframeshifting.Keywords:RNApseud

7、oknot;ribosomalframeshifting;coronavirus;translationalregulation;RNAstructure1.Introductionvertebrateretroviruses,Roussarcomavirus(RSVf)(Jacks&Varmus,1985)andmousemammaryVirusesemployawidevarietyofstrategiestotumourvirus(MMT