Antimicrobial activity of fusidic acid in Escherichia coli is dependent on the relative levels of ribosome recycling factor and elongation factor G

Abstract

During protein synthesis, elongation factor G (EFG) participates at the steps of translocation and ribosome recycling. Fusidic acid (FA) is a bacteriostatic antibiotic, which traps EFG on ribosomes, stalling them on mRNAs. How the bacterial susceptibility to FA is determined, and which of the two functions of EFG (translocation or ribosome recycling) is more vulnerable, has remained debatable. The in vivo studies addressing these aspects of FA mediated inhibition of protein synthesis are lacking. Here, we used a system of Escherichia coli strains and their complementation/supplementation with the plasmid borne copies of the inducible versions of EFG and ribosome recycling factor (RRF) genes. Additionally, we investigated FA sensitivity in a strain with increased proportion of stalled ribosomes. We show that the cells with high EFG/RRF (or low RRF/EFG) ratios are more susceptible to FA than those with low EFG/RRF (or high RRF/EFG) ratios. Our in vivo observations are consistent with the recent in vitro reports of dependence of FA susceptibility on EFG/RRF ratios, and the notion that an overriding target of FA is the translocation function of EFG. An applied outcome of our in vivo study is that FA mediated growth inhibition could be facilitated by depletion or inactivation of cellular RRF.

Systematic evolution of initiation factor 3 and the ribosomal protein uS12 optimizes Escherichia coli growth with an unconventional initiator tRNA

“…Thus, while the rpsL V32L allele augments RRF ts function, the rpsL H76L dampens it. Interestingly, the poor functioning of rpsL H76L (with RRF/EFG) is consistent with its hypersensitivity to fusidic acid (discussed below in Section 2.8) suggesting a more stable binding of EF‐G to ribosome (Ayyub et al., 2018b; Borg et al., 2016; Rao & Varshney, 2001), which would in turn avoid precedence of RRF binding to the ribosome, a pre‐requisite for productive ribosome recycling (Prabhakar et al., 2017).…”

Reversing the Natural Drug Resistance of Gram-Negative Bacteria to Fusidic Acid via Forming Drug–Phospholipid Complex

“…The antibacterial mechanism of FA is based on its irreversible binding to the elongation factor G (EF-G) located on the ribosome [11][12][13][14]. Consequently, the translocation of the nascent polypeptide chain from the A site to the P site, the formulation of the peptide bond and the release of the ribosome complex on reaching the stop codon are all blocked [15][16][17][18]. However, FA only has potent antibacterial activity against Gram-positive bacteria, and Gram-negative pathogens have natural resistance to FA [19][20][21].…”