trna in decoding and the

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1、tRNAinDecodingandtheSecondaryarticleWobbleHypothesisArticleContents.IntroductionMickFTuite,UniversityofKent,Canterbury,Kent,UK.CodonAssignments.The‘WobbleHypothesis’ThetranslationofthegeneticcodestoredinmessengerRNArequiressignificantlyfewer.Codon–AnticodonInteractionstranferRNAsthanthere

2、arecodons.Thisisachievedthroughanincreasedflexibilityinthe.AccuracyinDecodingallowablebase-pairinteractionsbetweenthemRNAandtRNAinvolvingthethirdpositionofthecodon.Therulesgoverningtheallowablebase-pairinteractionswereoriginallysummarizedinCrick’s‘wobblehypothesis’.Introduction(Figure1).S

3、uchspecificity,whiledependingtosomeextentonstandard‘Watson–Crick’basepairingrules(i.e.U:AorThegeneticinformationstoredinanewlysynthesizedG:C),showsamuchgreaterdegreeofflexibilityofmessengerRNA(mRNA)moleculeisdecodedbothallowablebase-pairinteractionsthanbetweenthecom-efficientlyandaccuratelyvi

4、atransientinteractionsbe-plementarystrandsof,forexample,thedouble-strandedtweenthemRNAandaseriesof‘adaptor’RNAmolecules,DNAmolecule.TheoutcomeofthisflexibilityisthatanthetransferRNAs(tRNAs).InanorderedseriesoforganismdoesnothavetoencodeauniquetRNAspeciesdecodingsteps,aminoacidscovalentlyli

5、nkedtotheforeachofthe61aminoacid-specifying(sense)codons,tRNAsarebroughttotheribosomeandassembledintowithmostorganismshavingbetween35and45differentthemRNA-directedpolypeptidechain.TheorderinwhichtRNAspecies.Forexample,theyeastSaccharomycestheaminoacidsaredeliveredtotheribosomebythecerevisi

6、aeencodes42differenttRNAs.tRNAsisdirectedbytheorderofthecodonsintheThetRNAmolecule,whichisasingleRNAchainoftranslatedregionofthemRNA.ThemRNAistranslatedusuallynomorethan90nucleotidesinlength,foldsintoaonecodonatatimeduringtheensuingelongationcyclethree-dimensionalL-shapedstructurecontainin

7、gasig-withtheincomingaminoacylatedtRNA(aa-tRNA)beingnificantlevelofsecondaryandtertiaryintramoleculardeliveredtotheribosomebyaproteinelongationfactorinteractionsbetweenbasesthroughhydrogenbonding.(EF-Tuinbacteria,eEF1Aineukaryotes).Thelargestunpairedregionofthemolecu