title: Pel is a cationic exopolysaccharide that cross-links extracellular DNA in the Pseudomonas aeruginosa biofilm matrix.
abstract: Biofilm formation is a complex, ordered process. In the opportunistic pathogen Pseudomonas aeruginosa, Psl and Pel exopolysaccharides and extracellular DNA (eDNA) serve as structural components of the biofilm matrix. Despite intensive study, Pel's chemical structure and spatial localization within mature biofilms remain unknown. Using specialized carbohydrate chemical analyses, we unexpectedly found that Pel is a positively charged exopolysaccharide composed of partially acetylated 1→4 glycosidic linkages of N-acetylgalactosamine and N-acetylglucosamine. Guided by the knowledge of Pel's sugar composition, we developed a tool for the direct visualization of Pel in biofilms by combining Pel-specific Wisteria floribunda lectin staining with confocal microscopy. The results indicate that Pel cross-links eDNA in the biofilm stalk via ionic interactions. Our data demonstrate that the cationic charge of Pel is distinct from that of other known P. aeruginosa exopolysaccharides and is instrumental in its ability to interact with other key biofilm matrix components.
authors: Department of Microbiology, University of Washington, Seattle, WA 98195;
authors: Laura K
authors: LK
authors: Jennings
authors: Department of Microbiology, University of Washington, Seattle, WA 98195;
authors: Kelly M
authors: KM
authors: Storek
authors: Department of Microbiology, University of Washington, Seattle, WA 98195;
authors: Hannah E
authors: HE
authors: Ledvina
authors: Equipe Biochimie des Produits Aquatiques, Université du Littoral-Côte d'Opale, 62327 Boulogne-sur-mer, France;
authors: Charlène
authors: C
authors: Coulon
authors: Program in Molecular Structure and Function, The Hospital for Sick Children, Toronto, ON, Canada M5G 0A1; Department of Biochemistry, Faculty of Medicine, University of Toronto, Toronto, ON, Canada M5S 1A8;
authors: Lindsey S
authors: LS
authors: Marmont
authors: Equipe Biochimie des Produits Aquatiques, Université du Littoral-Côte d'Opale, 62327 Boulogne-sur-mer, France;
authors: Irina
authors: http://orcid.org/0000-0002-7574-3824
authors: I
authors: Sadovskaya
authors: Department of Microbiology, University of Washington, Seattle, WA 98195;
authors: Patrick R
authors: PR
authors: Secor
authors: Department of Microbiology, University of Washington, Seattle, WA 98195;
authors: Boo Shan
authors: BS
authors: Tseng
authors: School of Pharmacy, University of Washington, Seattle, WA, 98195;
authors: Michele
authors: M
authors: Scian
authors: Division of Cell and Molecular Biology, Faculty of Natural Science, Center for Molecular Microbiology and Infection, Imperial College London, London SW7 2AZ, United Kingdom;
authors: Alain
authors: A
authors: Filloux
authors: Department of Microbial Infection and Immunity, The Ohio State University, Columbus, OH 43210; Department of Microbiology, The Ohio State University, Columbus, OH 43210; Center for Microbial Interface Biology, The Ohio State University, Columbus, OH 43210.
authors: Daniel J
authors: DJ
authors: Wozniak
authors: Program in Molecular Structure and Function, The Hospital for Sick Children, Toronto, ON, Canada M5G 0A1; Department of Biochemistry, Faculty of Medicine, University of Toronto, Toronto, ON, Canada M5S 1A8;
authors: P Lynne
authors: PL
authors: Howell
authors: Department of Microbiology, University of Washington, Seattle, WA 98195; parsem@u.washington.edu.
authors: Matthew R
authors: MR
authors: Parsek
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D018441:Biofilms; D002412:Cations / Q000737:chemistry; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D005109:Extracellular Matrix / Q000378:metabolism; D005110:Extracellular Space / Q000235:genetics; D016695:Glycosyltransferases / Q000235:genetics / Q000378:metabolism; D015151:Immunoblotting; D018613:Microscopy, Confocal; D009154:Mutation; D037121:Plant Lectins / Q000737:chemistry / Q000378:metabolism; D011135:Polysaccharides, Bacterial / Q000737:chemistry / Q000378:metabolism*; D011550:Pseudomonas aeruginosa / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D034781:Receptors, N-Acetylglucosamine / Q000737:chemistry / Q000378:metabolism; D013194:Staining and Labeling / Q000379:methods
chemical_list: D001426:Bacterial Proteins; D002412:Cations; D004269:DNA, Bacterial; D037121:Plant Lectins; D011135:Polysaccharides, Bacterial; D034781:Receptors, N-Acetylglucosamine; C040129:wisteria lectin; C064841:exopolysaccharide, Pseudomonas; D016695:Glycosyltransferases
keywords: Pel; Psl; biofilms; exopolysaccharide; extracellular DNA