Peptidyl-tRNAs promote translational frameshifting.
Programmed translational frameshifting is a ubiquitous, though rare, mechanism of gene expression in prokaryotes and eukaryotes. Research on many such sites has led to a general understanding that frameshifting depends on slippage of one or two ribosome-bound tRNAs on the mRNA. We recently found an example of an efficient frameshift in the Ty3 retrotransposon of the yeast Saccharomyces cerevisiae which occurs without tRNA slippage. Frameshifting appears to occur by misplacement of aminoacyl-tRNA in the ribosomal A site. Most of the eight tRNAs which induce measurable amounts of +1 frameshifting are predicted to slip only very poorly. In fact, frameshifting by tRNA slippage appears an unusual event in yeast, and where it occurs depends on peptidyl-tRNAs which employ two-out-of-three decoding. In addition, frameshifting either by slippage or by aminoacyl-tRNA misplacement depends on adequate availability of the first +1 frame tRNA. We present two models to explain how the tRNA which reads the shifted frame codon could promote +1 translational frameshifting.
Vimaladithan
A
A
Department of Biological Sciences/Program in Molecular and Cell Biology, University of Maryland, Baltimore 21228, USA.
Pande
S
S
Zhao
H
H
Farabaugh
P J
PJ
D001483:Base Sequence; D003062:Codon / Q000235:genetics; D018965:Frameshifting, Ribosomal; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism; D008954:Models, Biological; D020648:Peptide Elongation Factor 1; D010445:Peptide Elongation Factors / Q000235:genetics / Q000378:metabolism; D012346:RNA, Transfer, Amino Acyl / Q000235:genetics* / Q000378:metabolism*; D018626:Retroelements; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism
D003062:Codon; D005656:Fungal Proteins; D020648:Peptide Elongation Factor 1; D010445:Peptide Elongation Factors; D012346:RNA, Transfer, Amino Acyl; D018626:Retroelements; C019037:tRNA, peptidyl-