Genetic Analysis of Lipo-oligosaccharide Core Biosynthesis in Campylobacter jejuni 81-176

Department of Chemistry, North Carolina Agricultural and Technical State University, Greensboro, North Carolina 27411; the Department of Chemistry, University of Guelph, Guelph, ON, N1G 2W1, Canada; the National Research Council, Ottawa, ON, K4A 4G5, Canada; and the Enteric Diseases Department, Naval Medical Research Center, Silver Spring, Maryland 20910

^* To whom correspondence should be addressed. Email: patricia.guerry{at}med.navy.mil.

	Abstract

We report the isolation and characterization of the Campylobacter jejuni 81-176 lipooligosaccharide (LOS) core mutants, lgtF and galT. The lgtF gene of C. jejuni has been suggested to encode a two domain glucosyltransferase that is responsible for the transfer of a -1, 4 glucose residue on Hep I and a -1,2 glucose residue on Hep II. A site-specific mutation in the lgtF gene of C. jejuni 81-176 resulted in the expression of a truncated LOS, and complementation of the mutant in trans restored core mobility to that of wild-type. Mass spectrometry and nuclear magnetic resonance of the truncated LOS confirmed the loss of two glucose residues, a -1, 4 glucose on Hep I and a -1, 2 glucose on Hep II. Mutation of another gene, galT, encoding a glycosyltransferase that maps outside the region defined as the LOS biosynthetic locus in C. jejuni 81-176, resulted in loss of the -(1, 4)-galactose residue and all distal residues in the core. Both mutants invaded intestinal epithelial cells in vitro at levels comparable to wild-type, in marked contrast to the deeper inner core mutant, waaC. These studies have important implications for the role of LOS in the pathogenesis of Campylobacter-mediated infection.