title: P-cluster maturation on nitrogenase MoFe protein.
abstract: Biosynthesis of nitrogenase P-cluster has attracted considerable attention because it is biologically important and chemically unprecedented. Previous studies suggest that P-cluster is formed from a precursor consisting of paired [4Fe-4S]-like clusters and that P-cluster is assembled stepwise on MoFe protein, i.e., one cluster is assembled before the other. Here, we specifically tackle the assembly of the second P-cluster by combined biochemical and spectroscopic approaches. By using a P-cluster maturation assay that is based on purified components, we show that the maturation of the second P-cluster requires the concerted action of NifZ, Fe protein, and MgATP and that the action of NifZ is required before that of Fe protein/MgATP, suggesting that NifZ may act as a chaperone that facilitates the subsequent action of Fe protein/MgATP. Furthermore, we provide spectroscopic evidence that the [4Fe-4S] cluster-like fragments can be converted to P-clusters, thereby firmly establishing the physiological relevance of the previously identified P-cluster precursor.
authors.affiliation: Department of Molecular Biology and Biochemistry, University of California, Irvine, CA 92697, USA.
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: Markus W
authors.initials: MW
authors.lastname: Ribbe
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D016948:Azotobacter vinelandii / Q000201:enzymology / Q000235:genetics; D004926:Escherichia coli / Q000235:genetics; D017353:Gene Deletion; D005798:Genes, Bacterial; D007506:Iron-Sulfur Proteins / Q000235:genetics / Q000378:metabolism*; D008954:Models, Biological; D008983:Molybdoferredoxin / Q000737:chemistry* / Q000302:isolation & purification / Q000378:metabolism*; D013053:Spectrophotometry
chemical_list: D007506:Iron-Sulfur Proteins; D008983:Molybdoferredoxin; D000255:Adenosine Triphosphate