Apicella MA

Cunneen MM

Reeves PR

Sayers JR

Westphal O

ABSTRACT
          
            The O polysaccharide of the lipopolysaccharide (O antigen) of Gram-negative bacteria often serves as a receptor for bacteriophages that can make the phage dependent on a given O-antigen type, thus supporting the concept of the adaptive significance of the O-antigen variability in bacteria. The O-antigen layer also modulates interactions of many bacteriophages with their hosts, limiting the access of the viruses to other cell surface receptors. Here we report variations of O-antigen synthesis and structure in an environmental
            Escherichia coli
            isolate, 4s, obtained from horse feces, and its mutants selected for resistance to bacteriophage G7C, isolated from the same fecal sample. The 4s O antigen was found to be serologically, structurally, and genetically related to the O antigen of
            E. coli
            O22, differing only in side-chain α-
            d
            -glucosylation in the former, mediated by a
            gtr
            locus on the chromosome. Spontaneous mutations of
            E. coli
            4s occurring with an unusually high frequency affected either O-antigen synthesis or O-acetylation due to the inactivation of the gene encoding the putative glycosyltransferase WclH or the putative acetyltransferase WclK, respectively, by the insertion of IS
            1
            -like elements. These mutations induced resistance to bacteriophage G7C and also modified interactions of
            E. coli
            4s with several other bacteriophages conferring either resistance or sensitivity to the host. These findings suggest that O-antigen synthesis and O-acetylation can both ensure the specific recognition of the O-antigen receptor following infection by some phages and provide protection of the host cells against attack by other phages.
          </jats:p

Yuriy A. Knirel

Nikolai S. Prokhorov

Alexander S. Shashkov

Olga G. Ovchinnikova

Evelina L. Zdorovenko

Bin Liu

Elena S. Kostryukova

Andrey K. Larin

Alla K. Golomidova

Andrey V. Letarov

Crossref

Journal of Bacteriology

Variations in O-Antigen Biosynthesis and O-Acetylation Associated with Altered Phage Sensitivity in Escherichia coli 4s

Variations in O-Antigen Biosynthesis and O-Acetylation Associated with Altered Phage Sensitivity in Escherichia coli 4s

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