The Plesiomonas shigelloides wbO1 gene cluster and the role of O1-antigen LPS in pathogenicity

• The Plesiomonas shigelloides 302-73 strain (serotype O1) wb gene cluster.
• The cluster encodes 15 proteins in agreement with chemical structure.
• The mutants lacking this O1-antigen LPS unable to survive in serum or adhere.
• First report on genetics from a P. shigelloides O-antigen LPS not shared by Shigella.

The Plesiomonas shigelloides 302-73 strain (serotype O1) wb gene cluster encodes 15 proteins which are consistent with the chemical structure of the O1-antigen lypopolysaccharide (LPS) previously described for this strain. The P. shigelloides O1-antigen LPS export uses the Wzy-dependent pathway as correspond to heteropolysaccharides structures. By the isolation of two mutants lacking this O1-antigen LPS, we could establish that the presence of the O1-antigen LPS is crucial for to survive in serum mainly to become resistant to complement. Also, it is an important factor in the bacterial adhesion and invasion to some eukaryotic cells, and in the ability to form biofilms. This is the first report on the genetics from a P. shigelloides O-antigen LPS cluster (wb) not shared by Shigella like P. shigelloides O17, the only one reported until now.