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.

SUBMITTER: Tezcan FA 

PROVIDER: S-EPMC4304452 | biostudies-literature | 2015 Jan

REPOSITORIES: biostudies-literature