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Genetic and biochemical analyses of the Pseudomonas aeruginosa Psl exopolysaccharide reveal overlapping roles for polysaccharide synthesis enzymes in Psl and LPS production |
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| Authors: | Matthew S Byrd Irina Sadovskaya Evgueny Vinogradov Haiping Lu April B Sprinkle Stephen H Richardson Luyan Ma Brad Ralston Matthew R Parsek Erin M Anderson Joseph S Lam Daniel J Wozniak |
| Institution: | Department of Microbiology and Immunology, Wake Forest University School of Medicine, Winston-Salem, NC 27157, USA.; Laboratoire de Recherche sur les Biomatériaux et les Biotechnologies IFR 114, Universitédu Littoral-Côte d'Opale, Bassin Napoléon, BP 120, 62327 Boulogne-sur-mer, France.; Institute for Biological Sciences, National Research Council of Canada, 100 Sussex Drive, Ottawa, ON, Canada KIA OR6.; Center for Microbial Interface Biology, The Ohio State University, Columbus, OH 43210, USA.; Department of Microbiology, University of Washington, Seattle, WA, USA.; Department of Molecular and Cellular Biology, University of Guelph, Guelph, ON, Canada. |
| Abstract: | Exopolysaccharides contribute significantly to attachment and biofilm formation in the opportunisitc pathogen Pseudomonas aeruginosa . The Psl polysaccharide, which is synthesized by the p olysaccharide s ynthesis l ocus ( psl ), is required for biofilm formation in non-mucoid strains that do not rely on alginate as the principal biofilm polysaccharide. In-frame deletion and complementation studies of individual psl genes revealed that 11 psl genes, pslACDEFGHIJKL , are required for Psl production and surface attachment. We also present the first structural analysis of the psl -dependent polysaccharide, which consists of a repeating pentasaccharide containing d -mannose, d -glucose and l -rhamnose: In addition, we identified the sugar nucleotide precursors involved in Psl generation and demonstrated the requirement for GDP- d -mannose, UDP- d -glucose and dTDP- l -rhamnose in Psl production and surface attachment. Finally, genetic analyses revealed that wbpW restored Psl production in a pslB mutant and pslB promoted A-band LPS synthesis in a wbpW mutant, indicating functional redundancy and overlapping roles for these two enzymes. The structural and genetic data presented here provide a basis for further investigation of the Psl proteins and potential roles for Psl in the biology and pathogenesis of P. aeruginosa . |
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