期刊
JOURNAL OF MOLECULAR BIOLOGY
卷 417, 期 5, 页码 425-439出版社
ACADEMIC PRESS LTD- ELSEVIER SCIENCE LTD
DOI: 10.1016/j.jmb.2012.02.008
关键词
release factors RF1, RF2, RF3; ribosome recycling factor RRF; transfer-messenger RNA; tmRNA; peptidyl-tRNA hydrolase Pth; rescue of stalled ribosomes
资金
- Creative Biomedical Research Institute
- Consejo Nacional de Ciencia y Tecnologia, Mexico [54206]
During translation, ribosomes stall on mRNA when the aminoacyl-tRNA to be read is not readily available. The stalled ribosomes are deleterious to the cell and should be rescued to maintain its viability. To investigate the contribution of some of the cellular translation factors on ribosome rescuing, we provoked stalling at AGA codons in mutants that affected the factors and then analyzed the accumulation of oligopeptidyl (peptides of up to 6 amino acid residues, oligopep-)-tRNA or polypeptidyl (peptides of more than 300 amino acids in length, polypep-)-tRNA associated with ribosomes. Stalling was achieved by starvation for aminoacyl-tRNA(Arg4) upon induced expression of engineered lacZ (beta-ga/actosidase) reporter gene harboring contiguous AGA codons close to the initiation codon or at internal codon positions together with minigene ATGAGATAA accompanied by reduced peptidyl-tRNA hydrolase (Pth). Our results showed accumulations of peptidyl-tRNA associated with ribosomes in mutants for release factors (RF1, RF2, and RF3), ribosome recycling factor (RRF), Pth, and transfer-messenger RNA (tmRNA), implying that each of these factors cooperate in rescuing stalled ribosomes. The role of these factors in ribosome releasing from the stalled complex may vary depending on the length of the peptide in the peptidyl-tRNA. RF3 and RRF rescue stalled ribosomes by drop-off of peptidyl-tRNA, while RF1, RF2 (in the absence of termination codon), or Pth may rescue by hydrolyzing the associated peptidyl-tRNA. This is followed by the disassembly of the ribosomal complex of tRNA and mRNA by RRF and elongation factor G. (C) 2012 Elsevier Ltd. All rights reserved.
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