Mutational analysis of the redox-sensitive transcriptional regulator OxyR: regions important for DNA binding and multimerization.
OxyR is a LysR-type transcriptional regulator which negatively regulates its own expression and positively regulates the expression of proteins important for the defense against hydrogen peroxide in Escherichia coli and Salmonella typhimurium. Using random mutagenesis, we isolated six nonrepressing OxyR mutants that were impaired in DNA binding. Five of the mutations causing the DNA binding defect mapped near the N-terminal helix-turn-helix motif conserved among the LysR family members, confirming that this region is a DNA binding domain in OxyR. The sixth nonrepressing mutant (with E-225 changed to K [E225K]) was found to be predominantly dimeric, in contrast to the tetrameric wild-type protein, suggesting that a C-terminal region defined by the E225K mutation is involved in multimerization.
Kullik
I
I
Cell Biology and Metabolism Branch, National Institute of Child Health and Human Development, Bethesda, Maryland 20892.
Stevens
J
J
Toledano
M B
MB
Storz
G
G
D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism*; D001483:Base Sequence; D004252:DNA Mutational Analysis; D004269:DNA, Bacterial / Q000378:metabolism; D004268:DNA-Binding Proteins; D004926:Escherichia coli / Q000235:genetics*; D029968:Escherichia coli Proteins; D015964:Gene Expression Regulation, Bacterial; D008969:Molecular Sequence Data; D010084:Oxidation-Reduction; D018384:Oxidative Stress / Q000235:genetics*; D011485:Protein Binding; D011487:Protein Conformation; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D012097:Repressor Proteins; D017386:Sequence Homology, Amino Acid; D013329:Structure-Activity Relationship; D014157:Transcription Factors; D014158:Transcription, Genetic
D001426:Bacterial Proteins; D004269:DNA, Bacterial; D004268:DNA-Binding Proteins; D029968:Escherichia coli Proteins; D011993:Recombinant Fusion Proteins; D012097:Repressor Proteins; D014157:Transcription Factors; C499299:oxyR protein, E coli