EPR study of 1Asp-3Cys ligated 4Fe-4S iron-sulfur cluster in NB-protein (BchN-BchB) of a dark-operative protochlorophyllide reductase complex.
Dark-operative protochlorophyllide oxidoreductase, a nitrogenase-like enzyme, contains two [4Fe-4S] clusters, one in the L-protein ((BchL)(2)) and the other in the NB-protein ((BchN-BchB)(2)). The reduced NB-cluster in the NB-protein, which is ligated by 1Asp/3Cys residues, showed a broad S=3/2 electron paramagnetic resonance signal that is rather rare in [4Fe-4S] clusters. A 4Cys-ligated NB-cluster in the mutated variant BchB-D36C protein, in which the Asp36 was replaced by a Cys, gave a rhombic normal S=1/2 signal and lost the catalytic activity. The results suggest that Asp36 contributes to the low redox potential necessary to reduce protochlorophyllide.
Division of Material Science (Physics), Graduate School of Science, Nagoya University, Chikusa-ku, Nagoya, Japan. tkondo@bio.phys.nagoya-u.ac.jp
Toru
T
Kondo
Jiro
J
Nomata
Yuichi
Y
Fujita
Shigeru
S
Itoh
D000255:Adenosine Triphosphate / Q000378:metabolism; D019943:Amino Acid Substitution; D001224:Aspartic Acid / Q000235:genetics / Q000378:metabolism; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D002734:Chlorophyll / Q000378:metabolism; D003545:Cysteine / Q000235:genetics / Q000378:metabolism; D004578:Electron Spin Resonance Spectroscopy / Q000379:methods*; D007506:Iron-Sulfur Proteins / Q000235:genetics / Q000378:metabolism*; D005810:Multigene Family; D009591:Nitrogenase / Q000235:genetics / Q000378:metabolism*; D010084:Oxidation-Reduction; D044925:Oxidoreductases Acting on CH-CH Group Donors / Q000235:genetics / Q000378:metabolism*; D016354:Rhodobacter capsulatus / Q000201:enzymology / Q000235:genetics / Q000378:metabolism; D013696:Temperature
D001426:Bacterial Proteins; D007506:Iron-Sulfur Proteins; D002734:Chlorophyll; C064041:chlorophyll c; D001224:Aspartic Acid; D000255:Adenosine Triphosphate; D009591:Nitrogenase; D044925:Oxidoreductases Acting on CH-CH Group Donors; C023886:protochlorophyllide reductase; D003545:Cysteine