An intermediate state of bacterial ribosome dissociation is fixed by yeast mitochondrial initiation factor 3
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Abstract
The processes of association and dissociation of ribosomal subunits are of great importance for the protein biosynthesis. The mechanistic details of these processes, however, are not well known. In bacteria, upon translation termination, ribosome dissociates into subunits which is necessary for its further involvement into new initiation step. The dissociated state of ribosome is maintained by initiation factor 3 (IF3) which binds to free small subunits and prevents their premature association with the large subunits. In this work, we have exchanged IF3 in E.coli cells by its ortholog from Saccharomyces cerevisiae mitochondria (Aim23p) and showed that yeast protein cannot functionally substitute the bacterial one and is even slightly toxic for bacterial cells. Our in vitro experiments have demonstrated that Aim23p does not split E.coli ribosomes into subunits. Instead, it fixes an intermediate state of ribosomes dissociation characterized by sedimentation coefficient about 60S. Using molecular modeling, we show that such fixation is due to mitochondria-specific terminal extensions of Aim23p that stabilize the position of the protein on the bacterial ribosome.
Cite this as
2018. An intermediate state of bacterial ribosome dissociation is fixed by yeast mitochondrial initiation factor 3. PeerJ Preprints 6:e26997v1 https://doi.org/10.7287/peerj.preprints.26997v1note This preprint is not peer-reviewed. You may wish to reference the subsequent peer-reviewed version of this article.
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We understand the PeerJ Preprints policy and wish to proceed with publishing our work as a preprint.
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Supplemental Information
Raw data for Fig2D (initial scan of the Western-blotting results)
Initial modeling of Aim23p binding to 16S rRNA of E.coli
Aim23p is in green. Long unstructured extensions can be seen on the left side of the picture.
Script used for modeling of Aim23p binding to 30S ribosomal subunit
Additional Information
Competing Interests
The authors declare that they have no competing interests.
Author Contributions
Sergey Levitskii conceived and designed the experiments, performed the experiments, analyzed the data, prepared figures and/or tables, approved the final draft.
Ksenia Derbikova performed the experiments, analyzed the data, prepared figures and/or tables, approved the final draft.
Andrey V Golovin performed the experiments, analyzed the data, approved the final draft.
Anton Kuzmenko conceived and designed the experiments, performed the experiments, analyzed the data, approved the final draft.
Maria V Baleva performed the experiments, approved the final draft.
Ivan Chicherin performed the experiments, approved the final draft.
Igor A Krasheninnikov analyzed the data, prepared figures and/or tables, approved the final draft.
Piotr Kamenski conceived and designed the experiments, analyzed the data, prepared figures and/or tables, approved the final draft.
Data Deposition
The following information was supplied regarding data availability:
The raw data are provided in the supplementary tables 1 (all OD measurements for Fig.1) and 2-4 (all OD measurements for Fig.2), as well as supplementary figures 1 (initial scan of Western-blot results on Fig. 2D) and 2 (initial result of the molecular modeling). The script used for molecular modeling is also presented (as a html-file).
Funding
This work was supported by the Russian Science Foundation (Grant 17-14-01005 for experimental work and Grant 14-50-00029 for molecular modeling). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.