title: Alginate Biosynthesis Factories in Pseudomonas fluorescens: Localization and Correlation with Alginate Production Level.
abstract: Pseudomonas fluorescens is able to produce the medically and industrially important exopolysaccharide alginate. The proteins involved in alginate biosynthesis and secretion form a multiprotein complex spanning the inner and outer membranes. In the present study, we developed a method by which the porin AlgE was detected by immunogold labeling and transmission electron microscopy. Localization of the AlgE protein was found to depend on the presence of other proteins in the multiprotein complex. No correlation was found between the number of alginate factories and the alginate production level, nor were the numbers of these factories affected in an algC mutant that is unable to produce the precursor needed for alginate biosynthesis. Precursor availability and growth phase thus seem to be the main determinants for the alginate production rate in our strain. Clustering analysis demonstrated that the alginate multiprotein complexes were not distributed randomly over the entire outer cell membrane surface.
authors.affiliation: Department of Biotechnology, NTNU Norwegian University of Science and Technology, Trondheim, Norway.
authors.forename: Susan
authors.initials: S
authors.lastname: Maleki
authors.affiliation: Department of Biotechnology, NTNU Norwegian University of Science and Technology, Trondheim, Norway.
authors.forename: Eivind
authors.initials: E
authors.lastname: Almaas
authors.affiliation: Department of Biotechnology, NTNU Norwegian University of Science and Technology, Trondheim, Norway.
authors.forename: Sergey
authors.initials: S
authors.lastname: Zotchev
authors.affiliation: Department of Biotechnology, NTNU Norwegian University of Science and Technology, Trondheim, Norway.
authors.forename: Svein
authors.initials: S
authors.lastname: Valla
authors.affiliation: Department of Biotechnology, NTNU Norwegian University of Science and Technology, Trondheim, Norway helga.ertesvag@ntnu.no.
authors.forename: Helga
authors.identifier: http://orcid.org/0000-0001-9437-9469
authors.initials: H
authors.lastname: Ertesvåg
mesh_terms: D000464:Alginates; D020723:Glucuronic Acid / Q000096:biosynthesis; D006603:Hexuronic Acids; D026901:Membrane Transport Proteins / Q000032:analysis; D016253:Microscopy, Immunoelectron; D009097:Multienzyme Complexes / Q000032:analysis; D018272:Porins / Q000032:analysis; D011551:Pseudomonas fluorescens / Q000201:enzymology* / Q000378:metabolism*
chemical_list: D000464:Alginates; D006603:Hexuronic Acids; D026901:Membrane Transport Proteins; D009097:Multienzyme Complexes; D018272:Porins; D020723:Glucuronic Acid