title: Molecular structure and function of bacterial nitric oxide reductase.
abstract: The crystal structure of the membrane-integrated nitric oxide reductase cNOR from Pseudomonas aeruginosa was determined. The smaller NorC subunit of cNOR is comprised of 1 trans-membrane helix and a hydrophilic domain, where the heme c is located, while the larger NorB subunit consists of 12 trans-membrane helices, which contain heme b and the catalytically active binuclear center (heme b(3) and non-heme Fe(B)). The roles of the 5 well-conserved glutamates in NOR are discussed, based on the recently solved structure. Glu211 and Glu280 appear to play an important role in the catalytic reduction of NO at the binuclear center by functioning as a terminal proton donor, while Glu215 probably contributes to the electro-negative environment of the catalytic center. Glu135, a ligand for Ca(2+) sandwiched between two heme propionates from heme b and b(3), and the nearby Glu138 appears to function as a structural factor in maintaining a protein conformation that is suitable for electron-coupled proton transfer from the periplasmic region to the active site. On the basis of these observations, the possible molecular mechanism for the reduction of NO by cNOR is discussed. This article is part of a Special Issue entitled: Respiratory Oxidases.
authors: RIKEN SPring-8 Center, Sayo, Hyogo, Japan.
authors: Tomoya
authors: T
authors: Hino
authors: Shingo
authors: S
authors: Nagano
authors: Hiroshi
authors: H
authors: Sugimoto
authors: Takehiko
authors: T
authors: Tosha
authors: Yoshitsugu
authors: Y
authors: Shiro
mesh_terms: D001426:Bacterial Proteins / Q000737:chemistry* / Q000378:metabolism; D045304:Cytochromes c / Q000737:chemistry / Q000378:metabolism; D018698:Glutamic Acid / Q000737:chemistry / Q000378:metabolism; D006418:Heme / Q000737:chemistry / Q000378:metabolism; D008958:Models, Molecular; D010088:Oxidoreductases / Q000737:chemistry* / Q000378:metabolism; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D021122:Protein Subunits / Q000737:chemistry / Q000378:metabolism; D011550:Pseudomonas aeruginosa / Q000201:enzymology* / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; D021122:Protein Subunits; D018698:Glutamic Acid; D006418:Heme; D045304:Cytochromes c; D010088:Oxidoreductases; C034747:nitric-oxide reductase