Identification of three oligo-/polysaccharide-specific ligases in Yersinia enterocolitica.

In lipopolysaccharide (LPS) biosynthesis of gram-negative bacteria the lipid A-core oligosaccharide (LA-core) and O-polysaccharide (O-PS) biosynthesis pathways proceed separately and converge in periplasmic space where the waaL-encoded ligase joins O-PS onto LA-core. Enterobacterial common antigen (ECA) biosynthesis follows that of O-PS except that ECA is usually ligated to phosphatidylglycerol (PG) and only rarely to LA-core. In Yersinia enterocolitica serotype O:3 LPS is composed of LA-inner core (IC) onto which a homopolymeric O-PS, a hexasaccharide called outer core (OC), and/or ECA are ligated.

Characterization of the six glycosyltransferases involved in the biosynthesis of Yersinia enterocolitica serotype O:3 lipopolysaccharide outer core.

Yersinia enterocolitica (Ye) is a gram-negative bacterium; Ye serotype O:3 expresses lipopolysaccharide (LPS) with a hexasaccharide branch known as the outer core (OC). The OC is important for the resistance of the bacterium to cationic antimicrobial peptides and also functions as a receptor for bacteriophage phiR1-37 and enterocoliticin. The biosynthesis of the OC hexasaccharide is directed by the OC gene cluster that contains nine genes (wzx, wbcKLMNOPQ, and gne).

Identification and role of a 6-deoxy-4-keto-hexosamine in the lipopolysaccharide outer core of Yersinia enterocolitica serotype O:3.

The outer core (OC) region of Yersinia enterocolitica serotype O:3 lipopolysaccharide is a hexasaccharide essential for the integrity of the outer membrane. It is involved in resistance against cationic antimicrobial peptides and plays a role in virulence during early phases of infection. We show here that the proximal residue of the OC hexasaccharide is a rarely encountered 4-keto-hexosamine, 2-acetamido-2,6-dideoxy-D-xylo-hex-4-ulopyranose (Sugp) and that WbcP is a UDP-GlcNAc-4,6-dehydratase enzyme responsible for the biosynthesis of the nucleotide-activated form of this rare sugar converting UDP-2-acetamido-2-deoxy-D-glucopyranose (UDP-D-GlcpNAc) to UDP-2-acetamido-2,6-dideoxy-D-xylo-hex-4-ulopyranose (UDP- Sugp).

Yersiniophage phiR1-37 is a tailed bacteriophage having a 270 kb DNA genome with thymidine replaced by deoxyuridine.

Bacteriophage piR1-37 was isolated based on its ability to infect strain YeO3-R1, a virulence-plasmid-cured O antigen-negative derivative of Yersinia enterocolitica serotype O : 3. In this study, the phage receptor was found to be a structure in the outer core hexasaccharide of Y. enterocolitica O : 3 LPS.

Functional characterization of Gne (UDP-N-acetylglucosamine-4-epimerase), Wzz (chain length determinant), and Wzy (O-antigen polymerase) of Yersinia enterocolitica serotype O:8.

The lipopolysaccharide (LPS) O-antigen of Yersinia enterocolitica serotype O:8 is formed by branched pentasaccharide repeat units that contain N-acetylgalactosamine (GalNAc), L-fucose (Fuc), D-galactose (Gal), D-mannose (Man), and 6-deoxy-D-gulose (6d-Gul). Its biosynthesis requires at least enzymes for the synthesis of each nucleoside diphosphate-activated sugar precursor; five glycosyltransferases, one for each sugar residue; a flippase (Wzx); and an O-antigen polymerase (Wzy). As this LPS shows a characteristic preferred O-antigen chain length, the presence of a chain length determinant protein (Wzz) is also expected.