A bacterial elongation factor G homologue exclusively functions in ribosome recycling in the spirochaete Borrelia burgdorferi |
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Authors: | Takuma Suematsu Shin‐ichi Yokobori Hiroyuki Morita Shigeo Yoshinari Takuya Ueda Kiyoshi Kita Nono Takeuchi Yoh‐ichi Watanabe |
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Institution: | 1. Department of Biomedical Chemistry, Graduate School of Medicine, the University of Tokyo, 7‐3‐1 Hongo, Bunkyo‐ku, Tokyo 113‐0033, Japan.;2. Department of Molecular Biology, Tokyo University of Pharmacy and Life Sciences, 1432‐1 Horinouchi, Hachioji‐shi, Tokyo 192‐0392, Japan.;3. Department of Medical Genome Sciences, Graduate School of Frontier Sciences, the University of Tokyo, 5‐1‐5 Kashiwanoha, Kashiwa‐shi, Chiba 277‐8562, Japan. |
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Abstract: | Translation elongation factor G (EF‐G) in bacteria plays two distinct roles in different phases of the translation system. EF‐G catalyses the translocation of tRNAs on the ribosome in the elongation step, as well as the dissociation of the post‐termination state ribosome into two subunits in the recycling step. In contrast to this conventional view, it has very recently been demonstrated that the dual functions of bacterial EF‐G are distributed over two different EF‐G paralogues in human mitochondria. In the present study, we show that the same division of roles of EF‐G is also found in bacteria. Two EF‐G paralogues are found in the spirochaete Borrelia burgdorferi, EF‐G1 and EF‐G2. We demonstrate that EF‐G1 is a translocase, while EF‐G2 is an exclusive recycling factor. We further demonstrate that B. burgdorferi EF‐G2 does not require GTP hydrolysis for ribosome disassembly, provided that translation initiation factor 3 (IF‐3) is present in the reaction. These results indicate that two B. burgdorferi EF‐G paralogues are close relatives to mitochondrial EF‐G paralogues rather than the conventional bacterial EF‐G, in both their phylogenetic and biochemical features. |
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