title: Sucrose synthesis in the nitrogen-fixing Cyanobacterium Anabaena sp. strain PCC 7120 is controlled by the two-component response regulator OrrA.
abstract: The filamentous, nitrogen-fixing cyanobacterium Anabaena sp. strain PCC 7120 accumulates sucrose as a compatible solute against salt stress. Sucrose-phosphate synthase activity, which is responsible for the sucrose synthesis, is increased by salt stress, but the mechanism underlying the regulation of sucrose synthesis remains unknown. In the present study, a response regulator, OrrA, was shown to control sucrose synthesis. Expression of spsA, which encodes a sucrose-phosphate synthase, and susA and susB, which encode sucrose synthases, was induced by salt stress. In the orrA disruptant, salt induction of these genes was completely abolished. The cellular sucrose level of the orrA disruptant was reduced to 40% of that in the wild type under salt stress conditions. Moreover, overexpression of orrA resulted in enhanced expression of spsA, susA, and susB, followed by accumulation of sucrose, without the addition of NaCl. We also found that SigB2, a group 2 sigma factor of RNA polymerase, regulated the early response to salt stress under the control of OrrA. It is concluded that OrrA controls sucrose synthesis in collaboration with SigB2.
authors.affiliation: Department of Biological Sciences, Graduate School of Science and Engineering, Tokyo Metropolitan University, Hachioji, Tokyo, Japan Department of Biological Science, Faculty of Science and Engineering, Chuo University, Bunkyo-ku, Tokyo, Japan Precursory Research for Embryonic Science and Technology, Japan Science and Technology Agency, Kawaguchi, Saitama, Japan ehira@tmu.ac.jp.
authors.forename: Shigeki
authors.initials: S
authors.lastname: Ehira
authors.affiliation: Department of Biochemistry and Molecular Biology, Faculty of Science, Saitama University, Saitama, Japan.
authors.forename: Satoshi
authors.initials: S
authors.lastname: Kimura
authors.affiliation: Department of Biological Sciences, Graduate School of Science and Engineering, Tokyo Metropolitan University, Hachioji, Tokyo, Japan.
authors.forename: Shogo
authors.initials: S
authors.lastname: Miyazaki
authors.affiliation: Department of Biochemistry and Molecular Biology, Faculty of Science, Saitama University, Saitama, Japan Department of Biological Science, Faculty of Science and Engineering, Chuo University, Bunkyo-ku, Tokyo, Japan.
authors.forename: Masayuki
authors.initials: M
authors.lastname: Ohmori
mesh_terms: D017033:Anabaena / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D017353:Gene Deletion; D020869:Gene Expression Profiling; D015964:Gene Expression Regulation, Bacterial; D005964:Glucosyltransferases / Q000235:genetics / Q000378:metabolism; D009997:Osmotic Pressure; D012808:Sigma Factor / Q000378:metabolism; D012965:Sodium Chloride / Q000378:metabolism; D013395:Sucrose / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; C116149:OrrA protein, Anabaena sp.; C079011:SigB protein, Bacteria; D012808:Sigma Factor; D012965:Sodium Chloride; D013395:Sucrose; D005964:Glucosyltransferases; C022699:sucrose synthase; C022698:sucrose-phosphate synthase