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A new and unexpected domain–domain interaction in the AraC protein
Author(s) -
Cole Stephanie Dirla,
Schleif Robert
Publication year - 2012
Publication title -
proteins: structure, function, and bioinformatics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.699
H-Index - 191
eISSN - 1097-0134
pISSN - 0887-3585
DOI - 10.1002/prot.24044
Subject(s) - l arabinose operon , arabinose , dna , tryptophan , chemistry , binding domain , dna binding domain , binding site , biophysics , domain (mathematical analysis) , biochemistry , stereochemistry , operon , biology , escherichia coli , gene , transcription factor , amino acid , xylose , fermentation , mathematical analysis , mathematics
An interaction between the dimerization domains and DNA binding domains of the dimeric AraC protein has previously been shown to facilitate repression of the Escherichia coli araBAD operon by AraC in the absence of arabinose. A new interaction between the domains of AraC in the presence of arabinose is reported here, the regulatory consequences of which are unknown. Evidence for the interaction is the following: the dissociation rate of arabinose‐bound AraC from half‐site DNA is considerably faster than that of free DNA binding domain, and the affinity of the dimerization domains for arabinose is increased when half‐site DNA is bound. In addition, an increase in the fluorescence intensity of tryptophan residues located in the arabinose‐bound dimerization domain is observed upon binding of half‐site DNA to the DNA binding domains. Direct physical evidence of the new domain–domain interaction is demonstrated by chemical crosslinking and NMR experiments. Proteins 2012;. © 2012 Wiley Periodicals, Inc.