title: Structural and mechanistic insights on nitrate reductases.
abstract: Nitrate reductases (NR) belong to the DMSO reductase family of Mo-containing enzymes and perform key roles in the metabolism of the nitrogen cycle, reducing nitrate to nitrite. Due to variable cell location, structure and function, they have been divided into periplasmic (Nap), cytoplasmic, and membrane-bound (Nar) nitrate reductases. The first crystal structure obtained for a NR was that of the monomeric NapA from Desulfovibrio desulfuricans in 1999. Since then several new crystal structures were solved providing novel insights that led to the revision of the commonly accepted reaction mechanism for periplasmic nitrate reductases. The two crystal structures available for the NarGHI protein are from the same organism (Escherichia coli) and the combination with electrochemical and spectroscopic studies also lead to the proposal of a reaction mechanism for this group of enzymes. Here we present an overview on the current advances in structural and functional aspects of bacterial nitrate reductases, focusing on the mechanistic implications drawn from the crystallographic data.
authors.affiliation: Departamento de Química, Faculdade de Ciências e Tecnologia, UCIBIO@REQUIMTE, Universidade Nova de Lisboa, Caparica, 2829-516, Portugal.
authors.forename: Catarina
authors.identifier: http://orcid.org/0000-0003-1852-5406
authors.initials: C
authors.lastname: Coelho
authors.affiliation: Departamento de Química, Faculdade de Ciências e Tecnologia, UCIBIO@REQUIMTE, Universidade Nova de Lisboa, Caparica, 2829-516, Portugal.
authors.forename: Maria João
authors.initials: MJ
authors.lastname: Romão
mesh_terms: D001419:Bacteria / Q000737:chemistry / Q000201:enzymology*; D001426:Bacterial Proteins / Q000737:chemistry / Q000378:metabolism; D020134:Catalytic Domain; D002462:Cell Membrane / Q000378:metabolism; D018360:Crystallography, X-Ray; D003593:Cytoplasm / Q000378:metabolism; D008958:Models, Molecular; D050901:Nitrate Reductase / Q000737:chemistry* / Q000378:metabolism*; D019897:Periplasm / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; D050901:Nitrate Reductase
keywords: DMSO reductase family; crystal structure; enzymatic mechanism; membrane-bound nitrate reductase; molybdenum enzymes; nitrogen cycle; periplasmic nitrate reductase