title: A new and unexpected domain-domain interaction in the AraC protein.
abstract: 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.
authors.affiliation: Department of Biology, Johns Hopkins University, Baltimore, Maryland 21218, USA.
authors.forename: Stephanie Dirla
authors.initials: SD
authors.lastname: Cole
authors.forename: Robert
authors.initials: R
authors.lastname: Schleif
mesh_terms: D051777:AraC Transcription Factor / Q000737:chemistry* / Q000378:metabolism*; D001089:Arabinose / Q000737:chemistry / Q000378:metabolism; D004247:DNA / Q000737:chemistry / Q000378:metabolism; D004591:Electrophoresis, Polyacrylamide Gel; D004926:Escherichia coli / Q000378:metabolism; D029968:Escherichia coli Proteins / Q000737:chemistry* / Q000378:metabolism*; D007700:Kinetics; D008958:Models, Molecular; D019906:Nuclear Magnetic Resonance, Biomolecular; D011485:Protein Binding; D054730:Protein Interaction Domains and Motifs
chemical_list: D051777:AraC Transcription Factor; C497371:AraC protein, E coli; D029968:Escherichia coli Proteins; D004247:DNA; D001089:Arabinose