title: Nitrogenase Fe protein-like Fe-S cluster is conserved in L-protein (BchL) of dark-operative protochlorophyllide reductase from Rhodobacter capsulatus.
abstract: Dark-operative protochlorophyllide reductase (DPOR) in bacteriochlorophyll biosynthesis is a nitrogenase-like enzyme consisting of L-protein (BchL-dimer) as a reductase component and NB-protein (BchN-BchB-heterotetramer) as a catalytic component. Metallocenters of DPOR have not been identified. Here we report that L-protein has an oxygen-sensitive [4Fe-4S] cluster similar to nitrogenase Fe protein. Purified L-protein from Rhodobacter capsulatus showed absorption spectra and an electron paramagnetic resonance signal indicative of a [4Fe-4S] cluster. The activity quickly disappeared upon exposure to air with a half-life of 20s. These results suggest that the electron transfer mechanism is conserved in nitrogenase Fe protein and DPOR L-protein.
authors.affiliation: Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya 464-8601, Japan.
authors.forename: Jiro
authors.initials: J
authors.lastname: Nomata
authors.forename: Masaharu
authors.initials: M
authors.lastname: Kitashima
authors.forename: Kazuhito
authors.initials: K
authors.lastname: Inoue
authors.forename: Yuichi
authors.initials: Y
authors.lastname: Fujita
mesh_terms: D001426:Bacterial Proteins / Q000737:chemistry; D017124:Conserved Sequence; D004578:Electron Spin Resonance Spectroscopy; D007506:Iron-Sulfur Proteins / Q000737:chemistry*; D045342:Light-Harvesting Protein Complexes / Q000737:chemistry*; D010088:Oxidoreductases / Q000737:chemistry*; D044925:Oxidoreductases Acting on CH-CH Group Donors / Q000737:chemistry*; D016354:Rhodobacter capsulatus / Q000201:enzymology*; D013057:Spectrum Analysis
chemical_list: D001426:Bacterial Proteins; D007506:Iron-Sulfur Proteins; D045342:Light-Harvesting Protein Complexes; D010088:Oxidoreductases; C029130:nitrogenase reductase; D044925:Oxidoreductases Acting on CH-CH Group Donors; C023886:protochlorophyllide reductase