Specific interaction between the ribosome recycling factor and the elongation factor G from Mycobacterium tuberculosis mediates peptidyl-tRNA release and ribosome recycling in Escherichia coli.
Once the translating ribosomes reach a termination codon, the nascent polypeptide chain is released in a factor-dependent manner. However, the P-site-bound deacylated tRNA and the ribosomes themselves remain bound to the mRNA (post-termination complex). The ribosome recycling factor (RRF) plays a vital role in dissociating this complex. Here we show that the Mycobacterium tuberculosis RRF (MtuRRF) fails to rescue Escherichia coli LJ14, a strain temperature-sensitive for RRF (frr(ts)). More interestingly, co-expression of M.tuberculosis elongation factor G (MtuEFG) with MtuRRF rescues the frr(ts) strain of E.coli. The simultaneous expression of MtuEFG is also needed to cause an enhanced release of peptidyl-tRNAs in E.coli by MtuRRF. These observations provide the first genetic evidence for a functional interaction between RRF and EFG. Both the in vivo and in vitro analyses suggest that RRF does not distinguish between the translating and terminating ribosomes for their dissociation from mRNA. In addition, complementation of E.coli PEM100 (fusA(ts)) with MtuEFG suggests that the mechanism of RRF function is independent of the translocation activity of EFG.
Rao
A R
AR
Department of Microbiology and Cell Biology, Indian Institute of Science, Bangalore, 560 012, India.
Varshney
U
U
D000595:Amino Acid Sequence; D003001:Cloning, Molecular; D004926:Escherichia coli / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D007700:Kinetics; D008969:Molecular Sequence Data; D009169:Mycobacterium tuberculosis / Q000235:genetics / Q000378:metabolism*; D020653:Peptide Elongation Factor G / Q000378:metabolism*; D010957:Plasmids; D011506:Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D012343:RNA, Transfer / Q000378:metabolism; D012346:RNA, Transfer, Amino Acyl / Q000378:metabolism*; D011994:Recombinant Proteins / Q000378:metabolism; D012269:Ribosomal Proteins; D012270:Ribosomes / Q000378:metabolism*; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D013696:Temperature
D020653:Peptide Elongation Factor G; D011506:Proteins; D012346:RNA, Transfer, Amino Acyl; D011994:Recombinant Proteins; D012269:Ribosomal Proteins; C087267:ribosome releasing factor; C019037:tRNA, peptidyl-; D012343:RNA, Transfer