Crystallographic analysis of the MoFe protein of nitrogenase from a nifV mutant of Klebsiella pneumoniae identifies citrate as a ligand to the molybdenum of iron molybdenum cofactor (FeMoco).
The x-ray crystal structure of NifV(-) Klebsiella pneumoniae nitrogenase MoFe protein (NifV(-) Kp1) has been determined and refined to a resolution of 1.9 A. This is the first structure for a nitrogenase MoFe protein with an altered cofactor. Moreover, it is the first direct evidence that the organic acid citrate is not just present, but replaces homocitrate as a ligand to the molybdenum atom of the iron molybdenum cofactor (FeMoco). Subsequent refinement of the structure revealed that the citrate was present at reduced occupancy.
Mayer
Suzanne M
SM
Department of Biological Chemistry, John Innes Centre, Norwich NR4 7UH, United Kingdom.
Gormal
Carol A
CA
Smith
Barry E
BE
Lawson
David M
DM
D002951:Citrates / Q000378:metabolism*; D018360:Crystallography, X-Ray; D007711:Klebsiella pneumoniae / Q000201:enzymology* / Q000235:genetics; D008024:Ligands; D008958:Models, Molecular; D008982:Molybdenum / Q000378:metabolism*; D008983:Molybdoferredoxin / Q000737:chemistry* / Q000378:metabolism*; D009154:Mutation; D009591:Nitrogenase / Q000737:chemistry*; D007652:Oxo-Acid-Lyases / Q000235:genetics*; D011487:Protein Conformation
D002951:Citrates; D008024:Ligands; D008983:Molybdoferredoxin; D008982:Molybdenum; D009591:Nitrogenase; C021365:homocitrate synthase; D007652:Oxo-Acid-Lyases