title: A mechanistic study on SMOB-ADP1: an NADH:flavin oxidoreductase of the two-component styrene monooxygenase of Acinetobacter baylyi ADP1.
abstract: Two styrene monooxygenase types, StyA/StyB and StyA1/StyA2B, have been described each consisting of an epoxidase and a reductase. A gene fusion which led to the chimeric reductase StyA2B and the occurrence in different phyla are major differences. Identification of SMOA/SMOB-ADP1 of Acinetobacter baylyi ADP1 may enlighten the gene fusion event since phylogenetic analysis indicated both proteins to be more related to StyA2B than to StyA/StyB. SMOB-ADP1 is classified like StyB and StyA2B as HpaC-like reductase. Substrate affinity and turnover number of the homo-dimer SMOB-ADP1 were determined for NADH (24 µM, 64 s(-1)) and FAD (4.4 µM, 56 s(-1)). SMOB-ADP1 catalysis follows a random sequential mechanism, and FAD fluorescence is quenched upon binding to SMOB-ADP1 (K d = 1.8 µM), which clearly distinguishes that reductase from StyB of Pseudomonas. In summary, this study confirmes made assumptions and provides phylogenetic and biochemical data for the differentiation of styrene monooxygenase-related flavin reductases.
authors.affiliation: Environmental Microbiology Group, Interdisciplinary Ecological Center, TU Bergakademie Freiberg, Leipziger Str. 29, 09599, Freiberg, Germany.
authors.forename: Janosch A D
authors.initials: JA
authors.lastname: Gröning
authors.forename: Stefan R
authors.initials: SR
authors.lastname: Kaschabek
authors.forename: Michael
authors.initials: M
authors.lastname: Schlömann
authors.forename: Dirk
authors.initials: D
authors.lastname: Tischler
mesh_terms: D000150:Acinetobacter / Q000201:enzymology* / Q000235:genetics; D000595:Amino Acid Sequence; D055162:Biocatalysis; D038181:FMN Reductase / Q000737:chemistry* / Q000145:classification / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D009243:NAD / Q000378:metabolism; D010088:Oxidoreductases / Q000378:metabolism; D010105:Oxygenases / Q000737:chemistry* / Q000145:classification / Q000235:genetics / Q000378:metabolism*; D010802:Phylogeny; D011549:Pseudomonas / Q000201:enzymology / Q000235:genetics
chemical_list: D009243:NAD; D010088:Oxidoreductases; C023111:epoxidase; D010105:Oxygenases; C026721:styrene monooxygenase; D038181:FMN Reductase