title: Substrate specificity and evolutionary implications of a NifDK enzyme carrying NifB-co at its active site.
abstract: The in vitro reconstitution of molybdenum nitrogenase was manipulated to generate a chimeric enzyme in which the active site iron-molybdenum cofactor (FeMo-co) is replaced by NifB-co. The NifDK/NifB-co enzyme was unable to reduce N(2) to NH(3), while exhibiting residual C(2)H(4) and considerable H(2) production activities. Production of H(2) by NifDK/NifB-co was stimulated by N(2) and was dependent on NifH and ATP hydrolysis. Thus, NifDK/NifB-co is a useful tool to gain insights into the catalytic mechanism of nitrogenase. Furthermore, phylogenetic analysis of D and K homologs indicates that several early emerging lineages, which contain NifB, NifH and NifDK encoding genes but which lack other genes required for processing NifB-co into FeMo-co, might encode an enzyme with similar catalytic properties to NifDK/NifB-co.
authors.affiliation: Institute of Biology/Microbiology, Martin-Luther University Halle-Wittenberg, Halle, Germany.
authors.forename: Basem
authors.initials: B
authors.lastname: Soboh
authors.forename: Eric S
authors.initials: ES
authors.lastname: Boyd
authors.forename: Dehua
authors.initials: D
authors.lastname: Zhao
authors.forename: John W
authors.initials: JW
authors.lastname: Peters
authors.forename: Luis M
authors.initials: LM
authors.lastname: Rubio
mesh_terms: D000114:Acetylene / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000378:metabolism; D020134:Catalytic Domain; D019143:Evolution, Molecular; D006859:Hydrogen / Q000378:metabolism; D058085:Iron Compounds / Q000378:metabolism*; D007711:Klebsiella pneumoniae / Q000201:enzymology; D008958:Models, Molecular; D008983:Molybdoferredoxin / Q000737:chemistry* / Q000378:metabolism*; D009584:Nitrogen / Q000378:metabolism; D010084:Oxidation-Reduction; D010802:Phylogeny; D013379:Substrate Specificity
chemical_list: D058085:Iron Compounds; D008983:Molybdoferredoxin; C085381:NifB cofactor; D006859:Hydrogen; D000255:Adenosine Triphosphate; D009584:Nitrogen; D000114:Acetylene