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.
Department of Biological Chemistry, John Innes Centre, Norwich NR4 7UH, United Kingdom.
Suzanne M
SM
Mayer
Carol A
CA
Gormal
Barry E
BE
Smith
David M
DM
Lawson
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