title: Dual functions of NifEN: insights into the evolution and mechanism of nitrogenase.
abstract: Nitrogenase catalyzes the nucleotide-dependent conversion of dinitrogen to ammonia at the iron-molybdenum cofactor (FeMoco) center of its molybdenum-iron (MoFe) protein component. Biosynthesis of FeMoco is arguably one of the most complex processes in the field of bioinorganic chemistry, which involves the participation of a number of nif (nitrogen fixing) gene products. One key player in this process, NifEN (encoded by nifE and nifN), is homologous to the MoFe protein with regard to both the primary sequences and the types of the metal centers. Recently, an all-iron precursor has been identified on NifEN, which closely resembles the Fe/S core structure of the mature cofactor. Such a precursor-bound form of NifEN has not only served as an excellent platform for the investigation of FeMoco assembly, but also facilitated the examination of the capacity of NifEN as a catalytic homolog of MoFe protein. This perspective will focus on the recent advances toward elucidating the dual functions of NifEN in nitrogenase assembly and catalysis, and the insights afforded by these advances into the evolution and mechanism of nitrogenase.
authors.affiliation: Department of Molecular Biology and Biochemistry, University of California, Irvine, CA 92697-3900, USA. yilinh@uci.edu mribbe@uci.edu
authors.forename: Yilin
authors.initials: Y
authors.lastname: Hu
authors.forename: Aaron W
authors.initials: AW
authors.lastname: Fay
authors.forename: Chi Chung
authors.initials: CC
authors.lastname: Lee
authors.forename: Jared A
authors.initials: JA
authors.lastname: Wiig
authors.forename: Markus W
authors.initials: MW
authors.lastname: Ribbe
mesh_terms: D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D005075:Biological Evolution; D004579:Electron Transport; D006864:Hydrogenase / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D008958:Models, Molecular; D008969:Molecular Sequence Data; D008982:Molybdenum / Q000737:chemistry / Q000378:metabolism; D008983:Molybdoferredoxin / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D009591:Nitrogenase / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D011487:Protein Conformation; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid
chemical_list: D001426:Bacterial Proteins; D008983:Molybdoferredoxin; D008982:Molybdenum; C043296:nickel-iron hydrogenase; D006864:Hydrogenase; D009591:Nitrogenase