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Biosynthesis of uronamide sugars in Pseudomonas aeruginosa O6 and Escherichia coli O121 O antigens
Author(s) -
King Jerry D.,
Vinogradov Evgeny,
Tran Vanessa,
Lam Joseph S.
Publication year - 2010
Publication title -
environmental microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.954
H-Index - 188
eISSN - 1462-2920
pISSN - 1462-2912
DOI - 10.1111/j.1462-2920.2010.02182.x
Subject(s) - biology , escherichia coli , biosynthesis , mutant , bacterial outer membrane , microbiology and biotechnology , biofilm , glutamine , biochemistry , antigen , pseudomonas aeruginosa , bacteria , gene , amino acid , genetics
Summary The major component of the outer leaflet of the outer membrane of Gram‐negative bacteria is lipopolysaccharide (LPS). The outermost domain of LPS is a polysaccharide called O antigen. Pseudomonas aeruginosa establishes biofilms on wet surfaces in a wide range of habitats and mutations in O‐antigen biosynthesis genes affect bacterial adhesion and the structure of these biofilms. The P. aeruginosa O6 O antigen contains a 2‐acetamido‐2‐deoxy‐ d ‐galacturonamide ( d ‐GalNAcAN) residue. O‐antigen biosynthesis in this serotype requires the wbpS gene, which encodes a protein with conserved domains of the glutamine‐dependent amidotransferase family. Replacement of conserved amino acids in the N‐terminal glutaminase conserved domain of WbpS inhibited O‐antigen biosynthesis under restricted‐ammonia conditions, but not in rich media; suggesting that this domain functions to provide ammonia for O‐antigen biosynthesis under restricted‐ammonia conditions, by hydrolysis of glutamine. Escherichia coli O121 also produces a d ‐GalNAcAN‐containing O antigen, and possesses a homologue of wbpS called wbqG . An E. coli O121 wbqG mutant was cross‐complemented by providing wbpS in trans , and vice versa, showing that these two genes are functionally interchangeable. The E. coli O121 wbqG mutant O antigen contains 2‐acetamido‐2‐deoxy‐ d ‐galacturonate ( d ‐GalNAcA), instead of d ‐GalNAcAN, demonstrating that wbqG is specifically required for biosynthesis of the carboxamide in this sugar.