title: Structural evidence for asymmetrical nucleotide interactions in nitrogenase.
abstract: The roles of ATP hydrolysis in electron-transfer (ET) reactions of the nitrogenase catalytic cycle remain obscure. Here, we present a new structure of a nitrogenase complex crystallized with MgADP and MgAMPPCP, an ATP analogue. In this structure the two nucleotides are bound asymmetrically by the Fe-protein subunits connected to the two different MoFe-protein subunits. This binding mode suggests that ATP hydrolysis and phosphate release may proceed by a stepwise mechanism. Through the associated Fe-protein conformational changes, a stepwise mechanism is anticipated to prolong the lifetime of the Fe-protein-MoFe-protein complex and, in turn, could orchestrate the sequence of intracomplex ET required for substrate reduction.
authors.affiliation: Department of Chemistry and Biochemistry, University of California, San Diego , La Jolla, California 92093-0356, United States.
authors.forename: F Akif
authors.initials: FA
authors.lastname: Tezcan
authors.forename: Jens T
authors.initials: JT
authors.lastname: Kaiser
authors.forename: James B
authors.initials: JB
authors.lastname: Howard
authors.forename: Douglas C
authors.initials: DC
authors.lastname: Rees
mesh_terms: D000255:Adenosine Triphosphate / Q000031:analogs & derivatives / Q000737:chemistry* / Q000378:metabolism*; D006868:Hydrolysis; D008958:Models, Molecular; D015394:Molecular Structure; D008983:Molybdoferredoxin / Q000737:chemistry / Q000378:metabolism; D009591:Nitrogenase / Q000737:chemistry* / Q000378:metabolism*; D010710:Phosphates / Q000737:chemistry / Q000378:metabolism
chemical_list: D008983:Molybdoferredoxin; D010710:Phosphates; D000255:Adenosine Triphosphate; D009591:Nitrogenase