Abstract
Shigella is a well-known human pathogen causing dysentery and their typing is solely based on the O antigens. We investigated the chemical structure and gene cluster of
Shigella boydii type 16 O antigen. As judged by sugar and methylation analyses along with NMR spectroscopy data, the O antigen has an
O-acetylated branched pentasaccharide repeating O unit, which consists of two
d-mannose residues (
d-Man), one residue each of
d-glucuronic acid (
d-GlcA),
N-acetylglucosamine (
d-GlcNAc) and
d-galactose (
d-Gal), and the structure of the O unit was established. The O antigen gene cluster of
S. boydii type 16 was identified and shown to contain putative genes for the synthesis of GDP-
d-Man, genes encoding sugar transferases, O unit flippase (Wzx) and O antigen polymerase (Wzy) as expected. The function of the
wzy gene was characterized by mutation test. Genes specific to
S. boydii type 16 O antigen gene cluster were identified by screening 186
Escherichia coli and
Shigella type strains, and can be used to develop PCR assays for detection of type 16 strains.