title: Azoreductase from Rhodobacter sphaeroides AS1.1737 is a flavodoxin that also functions as nitroreductase and flavin mononucleotide reductase.
abstract: Previously reported azoreductase (AZR) from Rhodobacter sphaeroides AS1.1737 was shown to be a flavodoxin possessing nitroreductase and flavin mononucleotide (FMN) reductase activities. The structure model of AZR constructed with SWISS-MODEL displayed a flavodoxin-like fold with a three-layer alpha/beta/alpha structure. With nitrofurazone as substrate, the optimal pH value and temperature were 7.0 and 50 degrees C, respectively. AZR could reduce a number of nitroaromatic compounds including 2,4-dinitrotoluene, 2,6-dinitrotoluene, 3,5-dinitroaniline, and 2,4,6-trinitrotoluene (TNT). TNT resulted to be the most efficient nitro substrate and was reduced to hydroxylamino-dinitrotoluene. Both NADH and NADPH could serve as electron donors of AZR, where the latter was preferred. Externally added FMN was also reduced by AZR via ping-pong mechanism and was a competitive inhibitor of NADPH, methyl red, and nitrofurazone. AZR with broad substrate specificity is a member of a new nitro/FMN reductase family demonstrating potential application in bioremediation.
authors.affiliation: School of Environmental and Biological Science and Technology, Dalian University of Technology, 116024 Dalian, People's Republic of China. guangfeiliu@yahoo.com.cn
authors.forename: Guangfei
authors.initials: G
authors.lastname: Liu
authors.forename: Jiti
authors.initials: J
authors.lastname: Zhou
authors.forename: Hong
authors.initials: H
authors.lastname: Lv
authors.forename: Xuemin
authors.initials: X
authors.lastname: Xiang
authors.forename: Jing
authors.initials: J
authors.lastname: Wang
authors.forename: Mi
authors.initials: M
authors.lastname: Zhou
authors.forename: Yuanyuan
authors.initials: Y
authors.lastname: Qv
mesh_terms: D000595:Amino Acid Sequence; D038181:FMN Reductase / Q000737:chemistry / Q000378:metabolism*; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009247:NADH, NADPH Oxidoreductases / Q000737:chemistry / Q000378:metabolism*; D009601:Nitroreductases / Q000737:chemistry / Q000378:metabolism*; D012242:Rhodobacter sphaeroides / Q000201:enzymology*; D013379:Substrate Specificity
chemical_list: D038181:FMN Reductase; D009247:NADH, NADPH Oxidoreductases; D009601:Nitroreductases; C021106:azoreductase