title: Increased bioplastic production with an RNA polymerase sigma factor SigE during nitrogen starvation in Synechocystis sp. PCC 6803.
abstract: Because cyanobacteria directly harvest CO2 and light energy, their carbon metabolism is important for both basic and applied sciences. Here, we show that overexpression of the sigma factor sigE in Synechocystis sp. PCC 6803 widely changes sugar catabolism and increases production of the biodegradable polyester polyhydroxybutyrate (PHB) during nitrogen starvation. sigE overexpression elevates the levels of proteins implicated in glycogen catabolism, the oxidative pentose phosphate pathway, and polyhydroxyalkanoate biosynthesis. PHB accumulation is enhanced by sigE overexpression under nitrogen-limited conditions, yet the molecular weights of PHBs synthesized by the parental glucose-tolerant and sigE overexpression strain are similar. Although gene expression induced by nitrogen starvation is changed and other metabolites (such as GDP-mannose and citrate) accumulate under sigE overexpression, genetic engineering of this sigma factor altered the metabolic pathway from glycogen to PHB during nitrogen starvation.
authors.affiliation: 1RIKEN Center for Sustainable Resource Science, 1-7-22 Suehiro-cho, Tsurumi-ku, Yokohama, Kanagawa 230-0045, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Osanai
authors.forename: Keiji
authors.initials: K
authors.lastname: Numata
authors.forename: Akira
authors.initials: A
authors.lastname: Oikawa
authors.forename: Ayuko
authors.initials: A
authors.lastname: Kuwahara
authors.forename: Hiroko
authors.initials: H
authors.lastname: Iijima
authors.forename: Yoshiharu
authors.initials: Y
authors.lastname: Doi
authors.forename: Kan
authors.initials: K
authors.lastname: Tanaka
authors.forename: Kazuki
authors.initials: K
authors.lastname: Saito
authors.forename: Masami Yokota
authors.initials: MY
authors.lastname: Hirai
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism*; D006003:Glycogen / Q000235:genetics / Q000378:metabolism; D009584:Nitrogen / Q000378:metabolism*; D054813:Polyhydroxyalkanoates / Q000096:biosynthesis*; D012808:Sigma Factor / Q000235:genetics* / Q000378:metabolism*; D046939:Synechocystis / Q000235:genetics / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; D054813:Polyhydroxyalkanoates; D012808:Sigma Factor; C111259:sigE protein, Bacteria; D006003:Glycogen; D009584:Nitrogen
keywords: cyanobacteria; gene expression; metabolomics; nitrogen starvation; sugar metabolism