Abstract
The Bacillus subtilis redox regulator Fnr controls genes of the anaerobic metabolism in response to low oxygen tension. An unusual structure for the oxygen-sensing [4Fe-4S](2+) cluster was detected by a combination of genetic experiments with UV-visible and Mössbauer spectroscopy. Asp-141 was identified as the fourth iron-sulfur cluster ligand besides three Cys residues. Exchange of Asp-141 with Ala abolished functional in vivo complementation of an fnr knock-out strain by the mutagenized fnr gene and in vitro DNA binding of the recombinant regulator FnrD141A. In contrast, substitution of Asp-141 with Cys preserved [4Fe-4S](2+) structure and regulator function.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Amino Acid Substitution
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Aspartic Acid / chemistry
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Aspartic Acid / genetics
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Aspartic Acid / metabolism
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Bacillus subtilis / chemistry
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Bacillus subtilis / genetics
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Bacillus subtilis / metabolism*
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Bacterial Proteins / chemistry
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Bacterial Proteins / genetics
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Bacterial Proteins / metabolism*
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Iron-Sulfur Proteins / chemistry
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Iron-Sulfur Proteins / genetics
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Iron-Sulfur Proteins / metabolism*
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Ligands
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Mutation, Missense
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Protein Structure, Tertiary
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Transcription Factors / chemistry
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Transcription Factors / genetics
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Transcription Factors / metabolism*
Substances
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Bacterial Proteins
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Iron-Sulfur Proteins
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Ligands
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Transcription Factors
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Aspartic Acid