Ligand binding to the FeMo-cofactor: Structures of CO-bound and reactivated nitrogenase

Abstract

Making nitrogen available for biosynthesis Nitrogen gas (N 2 ) is abundant in Earth's atmosphere; however, it must be converted into a bioavailable form before it can be incorporated into biomolecules. The enzyme nitrogenase, which is made up of two metalloproteins, converts N 2 into bioavailable ammonia. One of these, the MoFe-protein, contains a complex metal center, the FeMo cofactor, where the triple N 2 bond is reduced. Understanding how nitrogenase achieves the reduction of N 2 has been a long-term goal. Spatzal et al. present the structure of MoFe-protein bound to carbon monoxide (see the Perspective by Hogbom). Although this is an inhibitor rather than the natural substrate, the structure gives insight into how the FeMo metallocluster rearranges to achieve substrate reduction. Science , this issue p. 1620