Site-specific release of nascent chains from ribosomes at a sense codon.
"2A" oligopeptides are autonomous elements containing a D(V/I)EXNPGP motif at the C terminus. Protein synthesis from an open reading frame containing an internal 2A coding sequence yields two separate polypeptides, corresponding to sequences up to and including 2A and those downstream. We show that the 2A reaction occurs in the ribosomal peptidyltransferase center. Ribosomes pause at the end of the 2A coding sequence, over the glycine and proline codons, and the nascent chain up to and including this glycine is released. Translation-terminating release factors eRF1 and eRF3 play key roles in the reaction. On the depletion of eRF1, a greater proportion of ribosomes extend through the 2A coding sequence, yielding the full-length protein. In contrast, impaired eRF3 GTPase activity leads to many ribosomes failing to translate beyond 2A. Further, high-level expression of a 2A peptide-containing protein inhibits the growth of cells compromised for release factor activity and leads to errors in stop codon recognition. We propose that the nascent 2A peptide interacts with ribosomes to drive a highly unusual and specific "termination" reaction, despite the presence of a proline codon in the A site. After this, the majority of ribosomes continue translation, generating the separate downstream product.
Doronina
Victoria A
VA
Institute for Cell and Molecular Biosciences, The Medical School, Newcastle University, Newcastle upon Tyne NE2 4HH, United Kingdom.
Wu
Cheng
C
de Felipe
Pablo
P
Sachs
Matthew S
MS
Ryan
Martin D
MD
Brown
Jeremy D
JD
D000595:Amino Acid Sequence; D000818:Animals; D002417:Cattle; D003062:Codon / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D008954:Models, Biological; D008969:Molecular Sequence Data; D016366:Open Reading Frames; D010454:Peptide Termination Factors / Q000378:metabolism; D010455:Peptides / Q000737:chemistry / Q000378:metabolism*; D014176:Protein Biosynthesis; D012346:RNA, Transfer, Amino Acyl / Q000378:metabolism; D012270:Ribosomes / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000166:cytology / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000378:metabolism
D003062:Codon; D010454:Peptide Termination Factors; D010455:Peptides; D012346:RNA, Transfer, Amino Acyl; D029701:Saccharomyces cerevisiae Proteins; C019037:tRNA, peptidyl-