Role of Gne and GalE in the Virulence of Aeromonas hydrophila Serotype O34

• DOI: 10.1128/jb.01260-06
• Publication Date: 2006-11-14T01:39:08Z
• Authors: Rocío Canals; Natalia Jiménez; Silvia Vilches; Miguel Regué; Susana Merino; Juan M. Tomás
• Keywords: DNA, Bacterial; Lipopolysaccharides; 0301 basic medicine; Sequence Homology, Amino Acid; Genetic Complementation Test; Molecular Sequence Data; O Antigens; Sequence Analysis, DNA; Aeromonas hydrophila; Mice; UDPglucose 4-Epimerase; 03 medical and health sciences; Carbohydrate Sequence; Oncorhynchus mykiss; Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; Gene Order; Mutation; Animals; Electrophoresis, Polyacrylamide Gel; Amino Acid Sequence; Carbohydrate Epimerases; Plasmids

ABSTRACT

The mesophilic Aeromonas hydrophila AH-3 (serotype O34) strain shows two different UDP-hexose epimerases in its genome: GalE (EC 3.1.5.2) and Gne (EC 3.1.5.7). Similar homologues were detected in the different mesophilic Aeromonas strains tested. GalE shows only UDP-galactose 4-epimerase activity, while Gne is able to perform a dual activity (mainly UDP- N -acetyl galactosamine 4-epimerase and also UDP-galactose 4-epimerase). We studied the activities in vitro of both epimerases and also in vivo through the lipopolysaccharide (LPS) structure of A. hydrophila gne mutants, A. hydrophila galE mutants, A. hydrophila galE-gne double mutants, and independently complemented mutants with both genes. Furthermore, the enzymatic activity in vivo, which renders different LPS structures on the mentioned A. hydrophila mutant strains or the complemented mutants, allowed us to confirm a clear relationship between the virulence of these strains and the presence/absence of the O34 antigen LPS.