Resuming translation on tmRNA: a unique mode of determining a reading frame

Citation
Kp. Williams et al., Resuming translation on tmRNA: a unique mode of determining a reading frame, EMBO J, 18(19), 1999, pp. 5423-5433
Citations number
32
Categorie Soggetti
Molecular Biology & Genetics
Journal title
EMBO JOURNAL
ISSN journal
02614189 → ACNP
Volume
18
Issue
19
Year of publication
1999
Pages
5423 - 5433
Database
ISI
SICI code
0261-4189(19991001)18:19<5423:RTOTAU>2.0.ZU;2-N
Abstract
The bacterial ribosome switches from an mRNA lacking an in-frame stop codon and resumes translation on a specialized RNA known as tmRNA, SsrA or 10Sa RNA. We find that the ribosome can reach and use the extreme 3' terminal co don of the defective mRNA prior to switching. The first triplet to be trans lated in tmRNA (the resume codon) is determined at two levels: distant elem ents in tmRNA restrict resume codon choice to a narrow window and local ups tream elements provide precision. Insights from a randomization-selection e xperiment secure the alignment of tmRNA sequences from diverse species. The triplet UA(A/G) (normally recognized as a stop codon by release factor-1) is strongly conserved two nucleotides upstream of the resume codon, The cen tral adenosine of this triplet is essential for tmRNA activity. The reading frame of tmRNA is determined differently from all other known reading fram es in that the first translated codon is not specified by a particular tRNA anticodon.