title: Carbohydrate metabolism in mutants of the cyanobacterium Synechococcus elongatus PCC 7942 defective in glycogen synthesis.
abstract: ADP-glucose pyrophosphorylase (AGPase) and glycogen synthase (GS) catalyze the first two reactions of glycogen synthesis in cyanobacteria. Mutants defective in each of these enzymes in Synechococcus elongatus PCC 7942 were constructed and characterized. Activities of the corresponding enzymes in the selected mutants were virtually undetectable, and their ability to synthesize glycogen was entirely abolished. The maximal activities of photosynthetic O(2) evolution and the rates of respiration in the dark were significantly decreased in the mutants compared to those in wild-type cells. Addition of 0.2 M NaCl or 3 mM H(2)O(2) to liquid cultures markedly inhibited the growth of the AGPase and GS mutants, while the same treatment had only marginal effects on the wild type. These results suggest a significant role for storage polysaccharides in tolerance to salt or oxidative stress.
authors.affiliation: Department of Biological Production, Faculty of Bioresource Sciences, Akita Prefectural University, Akita 010-0195, Japan. esuzuki@akita-pu.ac.jp
authors.forename: Eiji
authors.initials: E
authors.lastname: Suzuki
authors.forename: Hajime
authors.initials: H
authors.lastname: Ohkawa
authors.forename: Katsuya
authors.initials: K
authors.lastname: Moriya
authors.forename: Tatsuya
authors.initials: T
authors.lastname: Matsubara
authors.forename: Yukari
authors.initials: Y
authors.lastname: Nagaike
authors.forename: Ikuko
authors.initials: I
authors.lastname: Iwasaki
authors.forename: Shoko
authors.initials: S
authors.lastname: Fujiwara
authors.forename: Mikio
authors.initials: M
authors.lastname: Tsuzuki
authors.forename: Yasunori
authors.initials: Y
authors.lastname: Nakamura
mesh_terms: D050260:Carbohydrate Metabolism; D002241:Carbohydrates / Q000032:analysis; D002734:Chlorophyll / Q000032:analysis; D000077194:Chlorophyll A; D051599:Glucose-1-Phosphate Adenylyltransferase / Q000235:genetics / Q000378:metabolism; D006003:Glycogen / Q000096:biosynthesis*; D006006:Glycogen Synthase / Q000235:genetics / Q000378:metabolism; D006861:Hydrogen Peroxide / Q000494:pharmacology; D009154:Mutation / Q000235:genetics*; D018384:Oxidative Stress / Q000187:drug effects; D010100:Oxygen / Q000032:analysis; D010788:Photosynthesis / Q000187:drug effects; D010798:Phycocyanin / Q000032:analysis; D012965:Sodium Chloride / Q000494:pharmacology; D046940:Synechococcus / Q000201:enzymology* / Q000235:genetics* / Q000254:growth & development
chemical_list: D002241:Carbohydrates; D010798:Phycocyanin; D002734:Chlorophyll; D012965:Sodium Chloride; D006003:Glycogen; D006861:Hydrogen Peroxide; D006006:Glycogen Synthase; D051599:Glucose-1-Phosphate Adenylyltransferase; D010100:Oxygen; D000077194:Chlorophyll A