Mutations in PurBox1 of the Bacillus subtilis pur operon control site affect adenine-regulated expression in vivo.
Transcription of the Bacillus subtilis pur operon is regulated by a purine repressor (PurR)-DNA control site interaction. The pur operon control site has two PurBoxes that are required for high-affinity PurR binding. An upstream, strong-binding PurBox1 is at position -81 to -68 relative to the transcription start site and a downstream weak-binding PurBox2 is at position -49 to -36. We constructed three PurBox1 mutations and the effects on binding of PurR to the control region in vitro and on regulation of pur operon expression in vivo were investigated. The mutations significantly reduced the binding of PurR to control region DNA. In strains with G-75A, G-75T and a five bp deletion (delta5) pur operon repression was defective in vivo. In addition in vivo PurR titration was used to confirm that sequences flanking PurBox1 and PurBox2 are required for PurR binding to the puroperon control site.
Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China.
Jinsong
J
Xuan
Howard
H
Zalkin
Manli
M
Weng
D000225:Adenine / Q000378:metabolism*; D001412:Bacillus subtilis / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism; D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism; D015964:Gene Expression Regulation, Bacterial; D009154:Mutation; D009875:Operator Regions, Genetic; D009876:Operon; D012097:Repressor Proteins / Q000235:genetics* / Q000378:metabolism; D001616:beta-Galactosidase / Q000032:analysis
D001426:Bacterial Proteins; C065825:PurR protein, Bacteria; D012097:Repressor Proteins; D001616:beta-Galactosidase; D000225:Adenine