title: Composition of the carbohydrate granules of the cyanobacterium, Cyanothece sp. strain ATCC 51142.
abstract: Cyanothece sp. strain ATCC 51142 is an aerobic, unicellular, diazotrophic cyanobacterium that temporally separates O2-sensitive N2 fixation from oxygenic photosynthesis. The energy and reducing power needed for N2 fixation appears to be generated by an active respiratory apparatus that utilizes the contents of large interthylakoidal carbohydrate granules. We report here on the carbohydrate and protein composition of the granules of Cyanothece sp. strain ATCC 51142. The carbohydrate component is a glucose homopolymer with branches every nine residues and is chemically identical to glycogen. Granule-associated protein fractions showed temporal changes in the number of proteins and their abundance during the metabolic oscillations observed under diazotrophic conditions. There also were temporal changes in the protein pattern of the granule-depleted supernatant fractions from diazotrophic cultures. None of the granule-associated proteins crossreacted with antisera directed against several glycogen-metabolizing enzymes or nitrogenase, although these proteins were tentatively identified in supernatant fractions. It is suggested that the granule-associated proteins are structural proteins required to maintain a complex granule architecture.
authors.affiliation: Department of Biological Sciences and NASA Specialized Center of Research and Training, Purdue University, West Lafayette, IN 47907, USA.
authors.forename: M A
authors.initials: MA
authors.lastname: Schneegurt
authors.forename: D M
authors.initials: DM
authors.lastname: Sherman
authors.forename: L A
authors.initials: LA
authors.lastname: Sherman
mesh_terms: D015061:1,4-alpha-Glucan Branching Enzyme / Q000378:metabolism; D001426:Bacterial Proteins / Q000276:immunology / Q000302:isolation & purification; D000458:Cyanobacteria / Q000737:chemistry* / Q000254:growth & development; D003594:Cytoplasmic Granules / Q000737:chemistry* / Q000648:ultrastructure; D004591:Electrophoresis, Polyacrylamide Gel; D005947:Glucose / Q000737:chemistry; D051599:Glucose-1-Phosphate Adenylyltransferase; D005964:Glucosyltransferases / Q000378:metabolism; D006003:Glycogen / Q000737:chemistry / Q000378:metabolism; D006006:Glycogen Synthase / Q000378:metabolism; D015151:Immunoblotting; D008854:Microscopy, Electron; D009586:Nitrogen Fixation; D009591:Nitrogenase / Q000378:metabolism; D009713:Nucleotidyltransferases / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; D006003:Glycogen; D009591:Nitrogenase; D005964:Glucosyltransferases; C033938:maltodextrin phosphorylase; D006006:Glycogen Synthase; D015061:1,4-alpha-Glucan Branching Enzyme; D009713:Nucleotidyltransferases; D051599:Glucose-1-Phosphate Adenylyltransferase; D005947:Glucose