Abstract
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.
Copyright © 2010 Federation of European Biochemical Societies. Published by Elsevier B.V. All rights reserved.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Adenosine Triphosphate / metabolism
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Amino Acid Substitution
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Aspartic Acid / genetics
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Aspartic Acid / metabolism
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Bacterial Proteins / genetics
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Bacterial Proteins / metabolism
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Chlorophyll / metabolism
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Cysteine / genetics
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Cysteine / metabolism
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Electron Spin Resonance Spectroscopy / methods*
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Iron-Sulfur Proteins / genetics
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Iron-Sulfur Proteins / metabolism*
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Multigene Family
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Nitrogenase / genetics
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Nitrogenase / metabolism*
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Oxidation-Reduction
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Oxidoreductases Acting on CH-CH Group Donors / genetics
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Oxidoreductases Acting on CH-CH Group Donors / metabolism*
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Rhodobacter capsulatus / enzymology
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Rhodobacter capsulatus / genetics
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Rhodobacter capsulatus / metabolism
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Temperature
Substances
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Bacterial Proteins
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Iron-Sulfur Proteins
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Chlorophyll
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chlorophyll c
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Aspartic Acid
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Adenosine Triphosphate
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Nitrogenase
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Oxidoreductases Acting on CH-CH Group Donors
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protochlorophyllide reductase
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Cysteine