Loss of elongation factor P disrupts bacterial outer membrane integrity

J Bacteriol. 2012 Jan;194(2):413-25. doi: 10.1128/JB.05864-11. Epub 2011 Nov 11.


Elongation factor P (EF-P) is posttranslationally modified at a conserved lysyl residue by the coordinated action of two enzymes, PoxA and YjeK. We have previously established the importance of this modification in Salmonella stress resistance. Here we report that, like poxA and yjeK mutants, Salmonella strains lacking EF-P display increased susceptibility to hypoosmotic conditions, antibiotics, and detergents and enhanced resistance to the compound S-nitrosoglutathione. The susceptibility phenotypes are largely explained by the enhanced membrane permeability of the efp mutant, which exhibits increased uptake of the hydrophobic dye 1-N-phenylnaphthylamine (NPN). Analysis of the membrane proteomes of wild-type and efp mutant Salmonella strains reveals few changes, including the prominent overexpression of a single porin, KdgM, in the efp mutant outer membrane. Removal of KdgM in the efp mutant background ameliorates the detergent, antibiotic, and osmosensitivity phenotypes and restores wild-type permeability to NPN. Our data support a role for EF-P in the translational regulation of a limited number of proteins that, when perturbed, renders the cell susceptible to stress by the adventitious overexpression of an outer membrane porin.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Anti-Bacterial Agents / pharmacology
  • Bacterial Proteins / genetics
  • Bacterial Proteins / metabolism
  • Cell Membrane / physiology*
  • Detergents
  • Drug Resistance, Bacterial
  • Escherichia coli / genetics
  • Escherichia coli / metabolism
  • Gene Expression Regulation, Bacterial / physiology*
  • Mutation
  • Osmolar Concentration
  • Peptide Elongation Factors / genetics
  • Peptide Elongation Factors / metabolism*
  • Permeability
  • Plasmids
  • Salmonella typhimurium / cytology*
  • Salmonella typhimurium / genetics
  • Salmonella typhimurium / metabolism*
  • Up-Regulation


  • Anti-Bacterial Agents
  • Bacterial Proteins
  • Detergents
  • Peptide Elongation Factors
  • factor EF-P