Abstract
Elongation factor RbbA is required for ATP-dependent deacyl-tRNA release presumably after each peptide bond formation; however, there is no information about the cellular role. Proteomic analysis in Escherichia coli revealed that RbbA reciprocally co-purified with a conserved inner membrane protein of unknown function, YhjD. Both proteins are also physically associated with the 30S ribosome and with members of the lipopolysaccharide transport machinery. Genome-wide genetic screens of rbbA and yhjD deletion mutants revealed aggravating genetic interactions with mutants deficient in the electron transport chain. Cells lacking both rbbA and yhjD exhibited reduced cell division, respiration and global protein synthesis as well as increased sensitivity to antibiotics targeting the ETC and the accuracy of protein synthesis. Our results suggest that RbbA appears to function together with YhjD as part of a regulatory network that impacts bacterial oxidative phosphorylation and translation efficiency.
Highlights
Protein synthesis on ribosomes requires GTPase and ATPase factors
Using this stringent filtering criteria, we found RbbA bound to protein synthesis elongation factor EF-Tu (e.g. TufA and TufB), 30S (e.g. RpsE, RpsJ, RpsM, RpsN, RpsP, RpsS and RpsT) subunit ribosomal (r) proteins, to other cytoplasmic proteins involved in tRNA (e.g., CCA) and rRNA (e.g. Rng, RlmL) processing (Text S1) and with the release factor PrfA (Table S1)
The ribosome-dependent ATPase elongation factor, RbbA, belongs to a large class of ABC ATPases that act in a variety of small molecule transport mechanisms as well as in protein synthesis [37,38]
Summary
Protein synthesis on ribosomes requires GTPase and ATPase factors. During protein chain elongation, EF-Tu, a GTPase recruits the activated aminoacyl-tRNA to the ribosomal A-site. RbbA or Ribosome Bound ATPase, acts in conjunction with EFTu to poise the aminoacyl-tRNA on the ribosomal A-site [1]. The ribosome-dependent ATPase, RbbA in Escherichia coli, markedly stimulates synthesis in reconstituted extracts [3]. RbbA stimulates the ribosome-dependent hydrolysis of ATP after each peptide bond is formed upon release of each deacyl-tRNA, the energy requirements for synthesis correspondingly increase. In this context, and considering the total metabolic, energy demand imposed by the translation process [7], it seems reasonable to assume that this process is associated with an energy source to rapidly replenish energy and maintain cellular viability
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