Mutational analysis of residue roles in AraC function.
The previously isolated hemiplegic, induction-negative, repression-positive mutants, H80R and Y82C, were found to be defective in the binding of arabinose. Randomization of other residues close to arabinose in the three-dimensional structure of AraC or that make strong interactions with arabinose yielded induction-negative, repression-positive mutants. The induction and repression properties of mutants obtained by randomizing individual residues of the N-terminal arm of AraC allowed identification of the domain with which that residue very likely makes its predominant interactions. Residues 8-14 of the arm appear to make their predominant interaction with the DNA-binding domain. Although the side-chain of residue 15 interacts directly with arabinose bound to the N-terminal dimerization domain, the properties of mutant F15L indicate that this mutation increases the affinity of the arm for the DNA-binding domain.
Ross
Jennifer J
JJ
Department of Biology, Johns Hopkins University, 3400 N Charles Street, Baltimore, MD 21218, USA.
Gryczynski
Urszula
U
Schleif
Robert
R
D051777:AraC Transcription Factor; D001089:Arabinose / Q000378:metabolism; D001426:Bacterial Proteins; D001483:Base Sequence; D001665:Binding Sites; D003198:Computer Simulation; D004247:DNA / Q000235:genetics / Q000378:metabolism; D004252:DNA Mutational Analysis; D019281:Dimerization; D015964:Gene Expression Regulation, Bacterial; D008969:Molecular Sequence Data; D016296:Mutagenesis; D017354:Point Mutation; D017434:Protein Structure, Tertiary; D012097:Repressor Proteins / Q000235:genetics* / Q000378:metabolism*; D013050:Spectrometry, Fluorescence; D013329:Structure-Activity Relationship; D014157:Transcription Factors
D051777:AraC Transcription Factor; D001426:Bacterial Proteins; D012097:Repressor Proteins; D014157:Transcription Factors; D004247:DNA; D001089:Arabinose