title: Maturation of nitrogenase cofactor-the role of a class E radical SAM methyltransferase NifB.
abstract: Nitrogenase catalyzes the important reactions of N2-reduction, CO-reduction and CO2-reduction at its active cofactor site. Designated the M-cluster, this complex metallocofactor is assembled through the generation of a characteristic 8Fe-core before the insertion of Mo and homocitrate that completes the stoichiometry of the M-cluster. NifB catalyzes the crucial step of radical SAM-dependent carbide insertion that occurs concomitant with the insertion a '9th' sulfur and the rearrangement/coupling of two 4Fe-clusters into a complete 8Fe-core of the M-cluster. Further categorization of a family of NifB proteins as a new class of radical SAM methyltransferases suggests a general function of these proteins in complex metallocofactor assembly and provides a new platform for unveiling unprecedented chemical reactions catalyzed by biological systems.
authors.affiliation: Department of Molecular Biology and Biochemistry, University of California, Irvine, CA 92697-3900, United States. Electronic address: yilinh@uci.edu.
authors.forename: Yilin
authors.initials: Y
authors.lastname: Hu
authors.affiliation: Department of Molecular Biology and Biochemistry, University of California, Irvine, CA 92697-3900, United States; Department of Chemistry, University of California, Irvine, CA 92697-2025, United States. Electronic address: mribbe@uci.edu.
authors.forename: Markus W
authors.initials: MW
authors.lastname: Ribbe
mesh_terms: D000595:Amino Acid Sequence; D003461:Crystallography; D008780:Methyltransferases / Q000737:chemistry / Q000378:metabolism*; D009591:Nitrogenase / Q000378:metabolism*; D012436:S-Adenosylmethionine / Q000378:metabolism*; D017386:Sequence Homology, Amino Acid
chemical_list: D012436:S-Adenosylmethionine; D009591:Nitrogenase; D008780:Methyltransferases