title: NrrA directly regulates expression of the fraF gene and antisense RNAs for fraE in the heterocyst-forming cyanobacterium Anabaena sp. strain PCC 7120.
abstract: The heterocystous cyanobacterium Anabaena sp. strain PCC 7120 grows as linear multicellular filaments that can contain hundreds of cells. Heterocysts, which are specialized cells for nitrogen fixation, are regularly intercalated among photosynthetic vegetative cells, and these cells are metabolically dependent on each other. Thus, multicellularity is essential for diazotrophic growth of heterocystous cyanobacteria. In Anabaena sp. strain PCC 7120, the fraF gene, which is required to limit filament length, is induced by nitrogen deprivation. The fraF transcripts extend to the fraE gene, which lies on the opposite DNA strand and could possess dual functionality, mRNAs for fraF and antisense RNAs for fraE. In the present study, we found that NrrA, a nitrogen-regulated response regulator, directly regulated expression of fraF. Induction of fraF by nitrogen deprivation was abolished by the nrrA disruption. NrrA specifically bound to the promoter region of fraF, and recognized an inverted repeat sequence. Thus, it is concluded that NrrA controls expression of mRNAs for fraF and antisense RNAs for fraE in response to nitrogen deprivation.
authors.affiliation: PRESTO, Japan Science and Technology Agency, Kawaguchi, Saitama 332-0012, Japan.|Department of Biological Science, Faculty of Science and Engineering, Chuo University, Bunkyo-ku, Tokyo 112-8551, Japan.|Department of Biological Sciences, Graduate school of Science and Engineering, Tokyo Metropolitan University, Hachioji, Tokyo 192-0397, Japan.
authors.forename: Shigeki
authors.initials: S
authors.lastname: Ehira
authors.affiliation: Consolidated Research Institute for Advanced Science and Medical Care, Waseda University, Shinjuku-ku, Tokyo 162-8480, Japan.|Department of Biological Science, Faculty of Science and Engineering, Chuo University, Bunkyo-ku, Tokyo 112-8551, Japan.
authors.forename: Masayuki
authors.initials: M
authors.lastname: Ohmori
mesh_terms: D017033:Anabaena / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism*; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D015964:Gene Expression Regulation, Bacterial; D055786:Gene Knockout Techniques; D009584:Nitrogen / Q000378:metabolism*; D009586:Nitrogen Fixation; D016372:RNA, Antisense / Q000096:biosynthesis* / Q000235:genetics; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; D016372:RNA, Antisense; D014157:Transcription Factors; D009584:Nitrogen