PMID:11069917
| Citation |
Wu, M and Schleif, R (2001) Strengthened arm-dimerization domain interactions in AraC. J. Biol. Chem. 276:2562-4 |
|---|---|
| Abstract |
Constitutive mutations were sought and found in the N-terminal arm of the Escherichia coli regulatory protein of the arabinose operon, AraC protein. A new mutation, N16D, was of particular interest. Asn-16 is not seen in the crystal structure of the AraC dimerization domain determined in the absence of arabinose, because the N-terminal arm 18 residues are disordered, but in the presence of arabinose, residues 7-18 fold over the arabinose and make many interactions with it. In this state Asn-16 lies near two positively charged amino acids, Lys-43 and Arg-99. We propose that the introduction of the negatively charged aspartic residue at position 16 creates a charge-charge interaction network among Asp-16, Lys-43, and Arg-99 that holds the arm to the dimerization domain even in the absence of arabinose. This frees the DNA-binding domains and allows them to bind cis to I(1)-I(2) half-sites and activate transcription. Mutating the two positively charged residues to alanines individually and collectively decreased or eliminated the constitutivity created by the N16D mutation. |
| Links |
PubMed Online version:10.1074/jbc.M008705200 |
| Keywords |
AraC Transcription Factor; Arabinose/metabolism; Arginine; Aspartic Acid; Bacterial Proteins/genetics; Bacterial Proteins/metabolism; Dimerization; Escherichia coli Proteins; Gene Expression Regulation, Bacterial; Lysine; Models, Genetic; Mutation; Repressor Proteins/genetics; Repressor Proteins/metabolism; Transcription Factors |
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