title: A unique capsular polysaccharide structure from the psychrophilic marine bacterium Colwellia psychrerythraea 34H that mimics antifreeze (glyco)proteins.
abstract: The low temperatures of polar regions and high-altitude environments, especially icy habitats, present challenges for many microorganisms. Their ability to live under subfreezing conditions implies the production of compounds conferring cryotolerance. Colwellia psychrerythraea 34H, a γ-proteobacterium isolated from subzero Arctic marine sediments, provides a model for the study of life in cold environments. We report here the identification and detailed molecular primary and secondary structures of capsular polysaccharide from C. psychrerythraea 34H cells. The polymer was isolated in the water layer when cells were extracted by phenol/water and characterized by one- and two-dimensional NMR spectroscopy together with chemical analysis. Molecular mechanics and dynamics calculations were also performed. The polysaccharide consists of a tetrasaccharidic repeating unit containing two amino sugars and two uronic acids bearing threonine as substituent. The structural features of this unique polysaccharide resemble those present in antifreeze proteins and glycoproteins. These results suggest a possible correlation between the capsule structure and the ability of C. psychrerythraea to colonize subfreezing marine environments.
authors.affiliation: Department of Chemical Sciences, University of Naples Federico II , Complesso Universitario Monte S. Angelo, Via Cintia 4, 80126 Naples, Italy.
authors.forename: Sara
authors.initials: S
authors.lastname: Carillo
authors.forename: Angela
authors.initials: A
authors.lastname: Casillo
authors.forename: Giuseppina
authors.initials: G
authors.lastname: Pieretti
authors.forename: Ermenegilda
authors.initials: E
authors.lastname: Parrilli
authors.forename: Filomena
authors.initials: F
authors.lastname: Sannino
authors.forename: Maddalena
authors.initials: M
authors.lastname: Bayer-Giraldi
authors.forename: Sandro
authors.initials: S
authors.lastname: Cosconati
authors.forename: Ettore
authors.initials: E
authors.lastname: Novellino
authors.forename: Marcela
authors.initials: M
authors.lastname: Ewert
authors.forename: Jody W
authors.initials: JW
authors.lastname: Deming
authors.forename: Rosa
authors.initials: R
authors.lastname: Lanzetta
authors.forename: Gennaro
authors.initials: G
authors.lastname: Marino
authors.forename: Michelangelo
authors.initials: M
authors.lastname: Parrilli
authors.forename: Antonio
authors.initials: A
authors.lastname: Randazzo
authors.forename: Maria L
authors.initials: ML
authors.lastname: Tutino
authors.forename: M Michela
authors.initials: MM
authors.lastname: Corsaro
mesh_terms: D034241:Alteromonadaceae / Q000737:chemistry* / Q000166:cytology; D021301:Antifreeze Proteins / Q000737:chemistry* / Q000302:isolation & purification; D002236:Carbohydrate Conformation; D002240:Carbohydrate Sequence; D009682:Magnetic Resonance Spectroscopy; D056004:Molecular Dynamics Simulation; D008969:Molecular Sequence Data; D011134:Polysaccharides / Q000737:chemistry* / Q000302:isolation & purification
chemical_list: D021301:Antifreeze Proteins; D011134:Polysaccharides