Novel Coordination of Lipopolysaccharide Modifications in Vibrio cholerae promotes CAMP resistance

5 years ago

Novel Coordination of Lipopolysaccharide Modifications in Vibrio cholerae promotes CAMP resistance

Alexander A. Crofts, Jeremy C. Henderson, M. Stephen Trent, Carmen M. Herrera

In the environment and during infection, the human intestinal pathogen Vibrio cholerae must overcome noxious compounds that damage the bacterial outer membrane. The El Tor and classical biotypes of O1 V. cholerae show striking differences in their resistance to membrane disrupting cationic antimicrobial peptides (CAMPs), such as polymyxins. The classical biotype is susceptible to CAMPs, but current pandemic El Tor biotype isolates gain CAMP resistance by altering the net charge of their cell surface through glycine modification of lipid A. Here we report a second lipid A modification mechanism that only functions in the V. cholerae El Tor biotype. We identify a functional EptA ortholog responsible for the transfer of the amino-residue phosphoethanolamine (pEtN) to the lipid A of V. cholerae El Tor that is not functional in the classical biotype. We previously reported that mildly acidic growth conditions (pH 5.8) downregulate expression of genes encoding the glycine modification machinery. In this report, growth at pH 5.8 increases expression of eptA with concomitant pEtN modification suggesting coordinated regulation of these LPS modification systems. Similarly, efficient pEtN lipid A substitution is seen in the absence of lipid A glycinylation. We further demonstrate EptA orthologs from non-cholerae Vibrio species are functional. This article is protected by copyright. All rights reserved. A defining characteristic of Gram-negative bacteria is the presence of a unique glycolipid termed lipopolysaccharide. Antimicrobial peptides that are ubiquitous in nature target lipopolysaccharide eventually leading to cell damage. Here, we describe how Vibrio cholerae, the etiological agent of cholera, remodel their lipopolysaccharide structure to gain resistance to antimicrobial peptides

Publisher URL: http://onlinelibrary.wiley.com/resolve/doi

DOI: 10.1111/mmi.13835