eIF5B gates the transition from translation initiation to elongation
Translation initiation determines both the quantity and identity of the protein that is encoded in an mRNA by establishing the reading frame for protein synthesis. In eukaryotic cells, numerous translation initiation factors prepare ribosomes for polypeptide synthesis; however, the underlying dynami...
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Published in | Nature (London) Vol. 573; no. 7775; pp. 605 - 608 |
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Main Authors | , , , , , , , |
Format | Journal Article |
Language | English |
Published |
London
Nature Publishing Group UK
01.09.2019
Nature Publishing Group |
Subjects | |
Online Access | Get full text |
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Summary: | Translation initiation determines both the quantity and identity of the protein that is encoded in an mRNA by establishing the reading frame for protein synthesis. In eukaryotic cells, numerous translation initiation factors prepare ribosomes for polypeptide synthesis; however, the underlying dynamics of this process remain unclear
1
,
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. A central question is how eukaryotic ribosomes transition from translation initiation to elongation. Here we use in vitro single-molecule fluorescence microscopy approaches in a purified yeast
Saccharomyces cerevisiae
translation system to monitor directly, in real time, the pathways of late translation initiation and the transition to elongation. This transition was slower in our eukaryotic system than that reported for
Escherichia coli
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–
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. The slow entry to elongation was defined by a long residence time of eukaryotic initiation factor 5B (eIF5B) on the 80S ribosome after the joining of individual ribosomal subunits—a process that is catalysed by this universally conserved initiation factor. Inhibition of the GTPase activity of eIF5B after the joining of ribosomal subunits prevented the dissociation of eIF5B from the 80S complex, thereby preventing elongation. Our findings illustrate how the dissociation of eIF5B serves as a kinetic checkpoint for the transition from initiation to elongation, and how its release may be governed by a change in the conformation of the ribosome complex that triggers GTP hydrolysis.
Single-molecule dynamics reveal that the GTPase activity of eukaryotic initiation factor eIF5B serves as a kinetic checkpoint for the transition from translation initiation to elongation. |
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Bibliography: | ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23 Author Contributions J.W. performed all the biochemical and single-molecule experiments; J.W. analyzed the data with the help from J.C., A.P., and A.N.P.; J.W. prepared the samples, D.-H.C. and J.W. acquired and D.-H.C. processed the cryo-EM data; J.W. and J.D.P. conceived the project with input from A.G.J., C.P.L and A.N.P.; J.W., A.G.J., C.P.L., J.C., D.-H.C., and J.D.P. wrote the manuscript. |
ISSN: | 0028-0836 1476-4687 |
DOI: | 10.1038/s41586-019-1561-0 |