Substrate specificity and evolutionary implications of a NifDK enzyme carrying NifB-co at its active site.
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.
Soboh
Basem
B
Institute of Biology/Microbiology, Martin-Luther University Halle-Wittenberg, Halle, Germany.
Boyd
Eric S
ES
Zhao
Dehua
D
Peters
John W
JW
Rubio
Luis M
LM
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
D058085:Iron Compounds; D008983:Molybdoferredoxin; C085381:NifB cofactor; D006859:Hydrogen; D000255:Adenosine Triphosphate; D009584:Nitrogen; D000114:Acetylene