Heterogeneous pathways and timing of factor departure during translation initiation
| Autor: | Joseph D. Puglisi, Alexey Petrov, Albert Tsai, Jonas Korlach, Sotaro Uemura, R. Andrew Marshall |
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| Rok vydání: | 2012 |
| Předmět: |
Genetics
eIF2 Multidisciplinary Time Factors Prokaryotic initiation factor-2 Computational biology Ribosome Subunits Large Bacterial Biology Prokaryotic Initiation Factor-2 Internal ribosome entry site Eukaryotic translation RNA Transfer Eukaryotic initiation factor Escherichia coli Initiation factor Translation initiation complex Peptide Chain Initiation Translational Prokaryotic initiation factor |
| Zdroj: | Nature. 487(7407) |
| ISSN: | 1476-4687 |
| Popis: | A single-molecule approach is used to investigate the kinetics of assembly of the translation initiation complex, revealing that there is more than one pathway by which the necessary factors can assemble. Translation initiation involves the association of the two ribosomal subcomplexes and a host of initiation factors. Joseph Puglisi and colleagues use a sophisticated single-molecule approach to look at the kinetics of assembly of the translation initiation complex. They find that there is more than one pathway by which the factors can assemble, and identify the crucial event that transitions the complex from initiation to elongation. The initiation of translation establishes the reading frame for protein synthesis and is a key point of regulation1. Initiation involves factor-driven assembly at a start codon of a messenger RNA of an elongation-competent 70S ribosomal particle (in bacteria) from separated 30S and 50S subunits and initiator transfer RNA. Here we establish in Escherichia coli, using direct single-molecule tracking, the timing of initiator tRNA, initiation factor 2 (IF2; encoded by infB) and 50S subunit joining during initiation. Our results show multiple pathways to initiation, with orders of arrival of tRNA and IF2 dependent on factor concentration and composition. IF2 accelerates 50S subunit joining and stabilizes the assembled 70S complex. Transition to elongation is gated by the departure of IF2 after GTP hydrolysis, allowing efficient arrival of elongator tRNAs to the second codon presented in the aminoacyl-tRNA binding site (A site). These experiments highlight the power of single-molecule approaches to delineate mechanisms in complex multicomponent systems. |
| Databáze: | OpenAIRE |
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