Bacterial Wzx flippases translocate (flip) short oligosaccharide repeat units (O units) across the inner membrane into the periplasm, which is a critical step in the assembly of many O antigens, capsules and other surface polysaccharides. There is enormous diversity in O antigens and capsules in particular, even within species. Wzx proteins are similarly diverse, but it has been widely accepted that they have significant specificity only for the first sugar of an O unit. In this study, we analysed the Wzx from the Salmonella enterica group C2 O antigen gene cluster, which is a unique and divergent member of a set of gene clusters that produce galactose-initiated O antigens. We demonstrate that this Wzx has a strong preference for the presence of an abequose side-branch, which manifests in a reduction of long-chain O antigen and a major growth defect. This contributes to a growing body of evidence that, contrary to earlier proposals, Wzx flippases commonly exhibit a strong preference for the structure of their native O unit.
Lipopolysaccharide, gene cluster, glycobiology, flippase, O unit
NCBI PubMed ID: 25837817Publication DOI: 10.1093/femsle/fnv053Journal NLM ID: 7705721Publisher: Blackwell Publishing
Correspondence: peter.reeves@sydney.edu.au
Institutions: School of Molecular Bioscience, Charles Perkins Centre (D17), the University of Sydney, Camperdown, NSW 2006, Australia
Methods: PCR, SDS-PAGE, DNA techniques, genetic methods
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