tmRNA-induced release of messenger RNA from stalled ribosomes.
A ribosome stalled on a truncated mRNA in the eubacterial cell can be rescued by tmRNA via a process called trans-translation. We demonstrate here that release of truncated mRNAs from stalled ribosomes accelerates significantly already after trans-peptidation following tmRNA binding to the ribosome. However, rapid release of truncated mRNA requires EF-G-dependent translocation of peptidyl-tmRNA from the A to the P site of the ribosome. We show also that the rate of mRNA release before and after peptidyl-tmRNA translocation correlates well with the rate of dissociation of deacylated tRNA, indicating that mRNA is retained on the ribosome mainly through codon:anticodon interaction with tRNA. The rate of mRNA release is reduced for mRNAs with strong Shine-Dalgarno (SD)-like sequences in the vicinity of the truncation site as well as for mRNAs with long 3' extensions downstream from the P-site codon. The reduced rate of release in the former case was due to a persisting SD-anti SD interaction between mRNA and the ribosome.
Ivanova
Natalia
N
Department of Cell and Molecular Biology, BMC, Uppsala University, Box 596, S-75 124 Uppsala, Sweden.
Pavlov
Michael Y
MY
Ehrenberg
Måns
M
D001665:Binding Sites; D003062:Codon; D004926:Escherichia coli / Q000235:genetics*; D020653:Peptide Elongation Factor G; D014176:Protein Biosynthesis; D012329:RNA, Bacterial / Q000502:physiology*; D012333:RNA, Messenger / Q000378:metabolism*; D012346:RNA, Transfer, Amino Acyl; D012270:Ribosomes / Q000235:genetics*
D003062:Codon; D020653:Peptide Elongation Factor G; D012329:RNA, Bacterial; D012333:RNA, Messenger; D012346:RNA, Transfer, Amino Acyl; C096222:tmRNA