title: Involvement of thioredoxin on the scaffold activity of NifU in heterocyst cells of the diazotrophic cyanobacterium Anabaena sp. strain PCC 7120.
abstract: The diazotrophic cyanobacterium Anabaena sp. strain PCC 7120 (A.7120) differentiates into specialized heterocyst cells that fix nitrogen under nitrogen starvation conditions. Although reducing equivalents are essential for nitrogen fixation, little is known about redox systems in heterocyst cells. In this study, we investigated thioredoxin (Trx) networks in Anabaena using TrxM, and identified 16 and 38 candidate target proteins in heterocysts and vegetative cells, respectively, by Trx affinity chromatography (Motohashi et al. (Comprehensive survey of proteins targeted by chloroplast thioredoxin. Proc Natl Acad Sci USA, 2001; 98: , 11224-11229)). Among these, the Fe-S cluster scaffold protein NifU that facilitates functional expression of nitrogenase in heterocysts was found to be a potential TrxM target. Subsequently, we observed that the scaffold activity of N-terminal catalytic domain of NifU is enhanced in the presence of Trx-system, suggesting that TrxM is involved in the Fe-S cluster biogenesis.
authors.affiliation: Chemical Resources Laboratory, Tokyo Institute of Technology, Nagatsuta 4259, Midori-ku, Yokohama 226-8503, Japan; Core Research for Evolutional Science and Technology (CREST), Japan Science and Technology Agency (JST), Chiyoda-Ku, Tokyo 102-0076, Japan; and thisabor@res.titech.ac.jp.
authors.forename: Jiro
authors.initials: J
authors.lastname: Nomata
authors.affiliation: Chemical Resources Laboratory, Tokyo Institute of Technology, Nagatsuta 4259, Midori-ku, Yokohama 226-8503, Japan; thisabor@res.titech.ac.jp.
authors.forename: Maki
authors.initials: M
authors.lastname: Maeda
authors.affiliation: Chemical Resources Laboratory, Tokyo Institute of Technology, Nagatsuta 4259, Midori-ku, Yokohama 226-8503, Japan; Core Research for Evolutional Science and Technology (CREST), Japan Science and Technology Agency (JST), Chiyoda-Ku, Tokyo 102-0076, Japan; and.
authors.forename: Atsuko
authors.initials: A
authors.lastname: Isu
authors.affiliation: Department of Biological Sciences, Kanagawa University, Tsuchiya 2946, Hiratsuka, Kanagawa 259-1293, Japan.
authors.forename: Kazuhito
authors.initials: K
authors.lastname: Inoue
authors.affiliation: Chemical Resources Laboratory, Tokyo Institute of Technology, Nagatsuta 4259, Midori-ku, Yokohama 226-8503, Japan; Core Research for Evolutional Science and Technology (CREST), Japan Science and Technology Agency (JST), Chiyoda-Ku, Tokyo 102-0076, Japan; and thisabor@res.titech.ac.jp.
authors.forename: Toru
authors.initials: T
authors.lastname: Hisabori
mesh_terms: D017033:Anabaena / Q000235:genetics / Q000378:metabolism*; D001426:Bacterial Proteins / Q000096:biosynthesis* / Q000235:genetics; D002736:Chloroplasts / Q000235:genetics / Q000378:metabolism; D015964:Gene Expression Regulation, Bacterial; D009584:Nitrogen / Q000378:metabolism; D009586:Nitrogen Fixation / Q000235:genetics; D009591:Nitrogenase / Q000235:genetics; D013879:Thioredoxins / Q000096:biosynthesis / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; D013879:Thioredoxins; D009591:Nitrogenase; D009584:Nitrogen
keywords: cyanobacteria; heterocyst; nitrogen fixation; redox regulation; thioredoxin