A bacterial elongation factor G homologue exclusively functions in ribosome recycling in the spirochaete Borrelia burgdorferi.
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.
Department of Biomedical Chemistry, Graduate School of Medicine, the University of Tokyo, Tokyo, Japan.
Takuma
T
Suematsu
Shin-ichi
S
Yokobori
Hiroyuki
H
Morita
Shigeo
S
Yoshinari
Takuya
T
Ueda
Kiyoshi
K
Kita
Nono
N
Takeuchi
Yoh-ichi
Y
Watanabe
D025065:Borrelia burgdorferi / Q000201:enzymology* / Q000378:metabolism*; D016000:Cluster Analysis; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D006160:Guanosine Triphosphate / Q000378:metabolism; D006801:Humans; D008969:Molecular Sequence Data; D020653:Peptide Elongation Factor G / Q000378:metabolism*; D010802:Phylogeny; D039665:Prokaryotic Initiation Factor-3 / Q000378:metabolism; D014176:Protein Biosynthesis; D012269:Ribosomal Proteins / Q000378:metabolism; D012270:Ribosomes / Q000378:metabolism*; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid
D004269:DNA, Bacterial; D020653:Peptide Elongation Factor G; D039665:Prokaryotic Initiation Factor-3; D012269:Ribosomal Proteins; C087267:ribosome releasing factor; D006160:Guanosine Triphosphate