title: Structure of precursor-bound NifEN: a nitrogenase FeMo cofactor maturase/insertase.
abstract: NifEN plays an essential role in the biosynthesis of the nitrogenase iron-molybdenum (FeMo) cofactor (M cluster). It is an α(2)β(2) tetramer that is homologous to the catalytic molybdenum-iron (MoFe) protein (NifDK) component of nitrogenase. NifEN serves as a scaffold for the conversion of an iron-only precursor to a matured form of the M cluster before delivering the latter to its target location within NifDK. Here, we present the structure of the precursor-bound NifEN of Azotobacter vinelandii at 2.6 angstrom resolution. From a structural comparison of NifEN with des-M-cluster NifDK and holo NifDK, we propose similar pathways of cluster insertion for the homologous NifEN and NifDK proteins.
authors.affiliation: Division of Chemistry and Chemical Engineering, California Institute of Technology, Mail Code 114-96, Pasadena, CA 91125, USA.
authors.forename: Jens T
authors.initials: JT
authors.lastname: Kaiser
authors.forename: Yilin
authors.initials: Y
authors.lastname: Hu
authors.forename: Jared A
authors.initials: JA
authors.lastname: Wiig
authors.forename: Douglas C
authors.initials: DC
authors.lastname: Rees
authors.forename: Markus W
authors.initials: MW
authors.lastname: Ribbe
mesh_terms: D000595:Amino Acid Sequence; D016948:Azotobacter vinelandii / Q000737:chemistry* / Q000201:enzymology; D001426:Bacterial Proteins / Q000737:chemistry* / Q000378:metabolism; D018360:Crystallography, X-Ray; D008958:Models, Molecular; D008969:Molecular Sequence Data; D008983:Molybdoferredoxin / Q000737:chemistry* / Q000378:metabolism; D009591:Nitrogenase / Q000737:chemistry* / Q000378:metabolism; D055503:Protein Multimerization; D011498:Protein Precursors / Q000737:chemistry / Q000378:metabolism; D020836:Protein Structure, Quaternary; D017434:Protein Structure, Tertiary
chemical_list: D001426:Bacterial Proteins; D008983:Molybdoferredoxin; D011498:Protein Precursors; D009591:Nitrogenase