60S dynamic state of bacterial ribosome is fixed by yeast mitochondrial initiation factor 3

PeerJ

article

Sergey Levitskii¹  Ksenia Derbikova¹  Maria V. Baleva¹  Anton Kuzmenko¹  Andrey V. Golovin²  Ivan Chicherin¹  Igor A. Krasheninnikov¹  Piotr Kamenski¹ 

[1] Faculty of Biology, Moscow State University;Faculty of Bioengineering and Bioinformatics, Moscow State University;Institute of Molecular Medicine, Sechenov First Moscow State Medical University;Faculty of Computer Science, Higher School of Economics

关键词: Ribosome;    Initiation factor 3;    Subunit dissociation;    Translation;   

DOI  :  10.7717/peerj.5620

学科分类：社会科学、人文和艺术（综合）

来源: Inra

【 摘 要 】

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, the ribosome dissociates into subunits which is necessary for its further involvement into new initiation step. The dissociated state of the ribosome is maintained by initiation factor 3 (IF3) which binds to free small subunits and prevents their premature association with large subunits. In this work, we have exchanged IF3 in Escherichia 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 a state of ribosomes characterized by sedimentation coefficient about 60S which is not a stable structure but rather reflects a shift of dynamic equilibrium between associated and dissociated states of the ribosome. Mitochondria-specific terminal extensions of Aim23p are necessary for “60S state” formation, and molecular modeling results point out that these extensions might stabilize the position of the protein on the bacterial ribosome.

【 授权许可】

CC BY