Involvement of the rml locus in core oligosaccharide and O polysaccharide assembly in Pseudomonas aeruginosa.
نویسندگان
چکیده
L-Rhamnose (L-Rha) is a component of the lipopolysaccharide (LPS) core, several O antigen polysaccharides, and the cell surface surfactant rhamnolipid of Pseudomonas aeruginosa. In this study, four contiguous genes (rmlBDAC) responsible for the synthesis of dTDP-L-Rha in P. aeruginosa have been cloned and characterized. Non-polar chromosomal rmlC mutants were generated in P. aeruginosa strains PAO1 (serotype O5) and PAK (serotype O6) and LPS extracted from the mutants was analysed by SDS-PAGE and Western immunoblotting. rmlC mutants of both serotype O5 and serotype O6 synthesized a truncated core region which was unable to act as an attachment point for either A-band or B-band O antigen. A rmd rmlC PAO1 double mutant (deficient in biosynthesis of both D-Rha and L-Rha) was constructed to facilitate structural analysis of the mutant core region. This strain has an incomplete core oligosaccharide region and does not produce A-band O antigen. These results provide the genetic and structural evidence that L-Rha is the receptor on the P. aeruginosa LPS core for the attachment of O polysaccharides. This is the first report of a genetically defined mutation that affects the synthesis of a single sugar in the core oligosaccharide region of P. aeruginosa LPS, and provides further insight into the mechanisms of LPS biosynthesis and assembly in this bacterium.
منابع مشابه
Rhamnosyltransferase genes migA and wapR are regulated in a differential manner to modulate the quantities of core oligosaccharide glycoforms produced by Pseudomonas aeruginosa.
migA and wapR are rhamnosyltransferase genes involved in the biosynthesis of Pseudomonas aeruginosa lipopolysaccharide core oligosaccharide. Here, we show that preferential expression of migA and wapR correlated with the levels of uncapped and O polysaccharide-capped core, respectively. wapR is negatively regulated, while migA is positively regulated by RhlR/RhlI quorum sensing.
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ورودعنوان ژورنال:
- Microbiology
دوره 146 ( Pt 11) شماره
صفحات -
تاریخ انتشار 2000