Abstract
The sigma 70 subunit of E. coli RNA polymerase is required for sequence-specific recognition of promoter DNA. Genetic studies and sequence analysis have indicated that sigma 70 contains two specific DNA-binding domains that recognize the two conserved portions of the prokaryotic promoter. However, intact sigma 70 does not bind to DNA. Using C-terminal and internal polypeptides of sigma 70, carrying one or both putative DNA-binding domains, we demonstrate that sigma 70 does contain two DNA-binding domains, but that N-terminal sequences inhibit the ability of intact sigma 70 to bind to DNA. Thus, we propose that sigma 70 is a sequence-specific DNA-binding protein that normally functions through an allosteric interaction with the core subunits of RNA polymerase.
Publication types
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Research Support, Non-U.S. Gov't
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Research Support, U.S. Gov't, P.H.S.
MeSH terms
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Bacterial Proteins / genetics
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Bacterial Proteins / metabolism
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Binding Sites
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DNA, Bacterial / metabolism*
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DNA-Binding Proteins / genetics
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DNA-Directed RNA Polymerases / metabolism
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Escherichia coli / enzymology
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Glutathione / metabolism
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Glutathione Transferase / genetics
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Glutathione Transferase / metabolism
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Mutagenesis, Site-Directed
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Peptides / genetics
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Peptides / metabolism*
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Plasmids
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Promoter Regions, Genetic*
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Recombinant Fusion Proteins / genetics
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Recombinant Fusion Proteins / metabolism
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Sigma Factor / genetics
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Sigma Factor / metabolism*
Substances
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Bacterial Proteins
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DNA, Bacterial
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DNA-Binding Proteins
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Peptides
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Recombinant Fusion Proteins
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Sigma Factor
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Glutathione Transferase
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RNA polymerase sigma 70
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DNA-Directed RNA Polymerases
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Glutathione