NB-protein (BchN-BchB) of dark-operative protochlorophyllide reductase is the catalytic component containing oxygen-tolerant Fe-S clusters.
Dark-operative protochlorophyllide (Pchlide) oxidoreductase is a nitrogenase-like enzyme consisting of the two components, L-protein (BchL-dimer) and NB-protein (BchN-BchB-heterotetramer). Here, we show that NB-protein is the catalytic component with Fe-S clusters. NB-protein purified from Rhodobacter capsulatus bound Pchlide that was readily converted to chlorophyllide a upon the addition of L-protein and Mg-ATP. The activity of NB-protein was resistant to the exposure to air. A Pchlide-free form of NB-protein purified from a bchH-lacking mutant showed an absorption spectrum suggesting the presence of Fe-S centers. Together with the Fe and sulfide contents, these findings suggested that NB-protein carries two oxygen-tolerant [4Fe-4S] clusters.
Nomata
Jiro
J
Graduate School of Bioagricultural Sciences, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8601, Japan.
Ogawa
Takuro
T
Kitashima
Masaharu
M
Inoue
Kazuhito
K
Fujita
Yuichi
Y
D001426:Bacterial Proteins / Q000378:metabolism*; D001483:Base Sequence; D020134:Catalytic Domain; D017931:DNA Primers; D004578:Electron Spin Resonance Spectroscopy; D007506:Iron-Sulfur Proteins / Q000378:metabolism*; D044925:Oxidoreductases Acting on CH-CH Group Donors / Q000378:metabolism*; D010100:Oxygen / Q000378:metabolism*; D011485:Protein Binding
D001426:Bacterial Proteins; D017931:DNA Primers; D007506:Iron-Sulfur Proteins; D044925:Oxidoreductases Acting on CH-CH Group Donors; C023886:protochlorophyllide reductase; D010100:Oxygen