期刊
CELL REPORTS
卷 17, 期 1, 页码 11-18出版社
CELL PRESS
DOI: 10.1016/j.celrep.2016.08.085
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资金
- NIH [NIH R01GM093278, R01GM112641]
- Searle Scholars award
- Pew Scholar in the Biomedical Sciences award
- National Science Foundation [DBI-0922879]
- National Institute of General Medical Sciences from the NIH [P41 GM103403]
- NIH-ORIP HEI [S10 RR029205]
- DOE Office of Science [DE-AC02-06CH11357]
Termination of protein synthesis on the ribosome is catalyzed by release factors (RFs), which share a conserved glycine-glycine-glutamine (GGQ) motif. The glutamine residue is methylated in vivo, but a mechanistic understanding of its contribution to hydrolysis is lacking. Here, we show that the modification, apart from increasing the overall rate of termination on all dipeptides, substantially increases the rate of peptide release on a subset of amino acids. In the presence of unmethylated RFs, we measure rates of hydrolysis that are exceptionally slow on proline and glycine residues and approximately two orders of magnitude faster in the presence of the methylated factors. Structures of 70S ribosomes bound to methylated RF1 and RF2 reveal that the glutamine side-chain methylation packs against 23S rRNA nucleotide 2451, stabilizing the GGQ motif and placing the side-chain amide of the glutamine toward tRNA. These data provide a framework for understanding how release factor modifications impact termination.
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