title: NO formation by a catalytically self-sufficient bacterial nitric oxide synthase from Sorangium cellulosum.
abstract: The role of nitric oxide (NO) in the host response to infection and in cellular signaling is well established. Enzymatic synthesis of NO is catalyzed by the nitric oxide synthases (NOSs), which convert Arg into NO and citrulline using co-substrates O2 and NADPH. Mammalian NOS contains a flavin reductase domain (FAD and FMN) and a catalytic heme oxygenase domain (P450-type heme and tetrahydrobiopterin). Bacterial NOSs, while much less studied, were previously identified as only containing the heme oxygenase domain of the more complex mammalian NOSs. We report here on the characterization of a NOS from Sorangium cellulosum (both full-length, scNOS, and oxygenase domain, scNOSox). scNOS contains a catalytic, oxygenase domain similar to those found in the mammalian NOS and in other bacteria. Unlike the other bacterial NOSs reported to date, however, this protein contains a fused reductase domain. The scNOS reductase domain is unique for the entire NOS family because it utilizes a 2Fe2S cluster for electron transfer. scNOS catalytically produces NO and citrulline in the presence of either tetrahydrobiopterin or tetrahydrofolate. These results establish a bacterial electron transfer pathway used for biological NO synthesis as well as a unique flexibility in using different tetrahydropterin cofactors for this reaction.
authors.affiliation: Department of Chemistry, Department of Molecular and Cell Biology, California Institute for Quantitative Biosciences, and Division of Physical Biosciences, Lawrence Berkeley National Laboratory, and Miller Institute for Basic Science, University of California, Berkeley, CA 94720, USA.
authors.forename: Theodor
authors.initials: T
authors.lastname: Agapie
authors.forename: Sandy
authors.initials: S
authors.lastname: Suseno
authors.forename: Joshua J
authors.initials: JJ
authors.lastname: Woodward
authors.forename: Stefan
authors.initials: S
authors.lastname: Stoll
authors.forename: R David
authors.initials: RD
authors.lastname: Britt
authors.forename: Michael A
authors.initials: MA
authors.lastname: Marletta
mesh_terms: D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D001665:Binding Sites; D002384:Catalysis; D004578:Electron Spin Resonance Spectroscopy; D004579:Electron Transport; D004591:Electrophoresis, Polyacrylamide Gel; D006418:Heme / Q000737:chemistry / Q000378:metabolism; D007700:Kinetics; D008956:Models, Chemical; D008969:Molecular Sequence Data; D009231:Myxococcales / Q000201:enzymology* / Q000235:genetics; D009249:NADP / Q000737:chemistry / Q000378:metabolism; D009569:Nitric Oxide / Q000737:chemistry / Q000378:metabolism*; D019001:Nitric Oxide Synthase / Q000235:genetics / Q000378:metabolism*; D010084:Oxidation-Reduction; D010100:Oxygen / Q000737:chemistry / Q000378:metabolism; D011485:Protein Binding; D017386:Sequence Homology, Amino Acid; D013056:Spectrophotometry, Ultraviolet; D013379:Substrate Specificity
chemical_list: D001426:Bacterial Proteins; D009569:Nitric Oxide; D006418:Heme; D009249:NADP; D019001:Nitric Oxide Synthase; D010100:Oxygen