Similar to most Gram-negative bacteria, the outer leaflet of the outer membrane of Vibrio cholerae is comprised of lipopolysaccharide. Previous reports have proposed that V.cholerae serogroups O1 and O139 synthesize structurally different lipid A domains, which anchor lipopolysaccharide within the outer membrane. In the current study, intact lipid A species of V.cholerae O1 and O139 were analysed by mass spectrometry. We demonstrate that V.cholerae serogroups associated with human disease synthesize a similar asymmetrical hexa-acylated lipid A species, bearing a myristate (C14:0) and 3-hydroxylaurate (3-OH C12:0) at the 2'- and 3'-positions respectively. A previous report from our laboratory characterized the V.cholerae LpxL homologue Vc0213, which transfers a C14:0 to the 2'-position of the glucosamine disaccharide. Our current findings identify V.cholerae Vc0212 as a novel lipid A secondary hydroxy-acyltransferase, termed LpxN, responsible for transferring the 3-hydroxylaurate (3-OH C12:0) to the V.cholerae lipid A domain. Importantly, the presence of a 3-hydroxyl group on the 3'-linked secondary acyl chain was found to promote antimicrobial peptide resistance in V.cholerae; however, this functional group was not required for activation of the innate immune response.
ASJC Scopus subject areas
- Molecular Biology