Binding of NorR to three DNA sites is essential for promoter activation of the flavorubredoxin gene, the nitric oxide reductase of Escherichia coli.
NorR is a nitric oxide sensor that in Escherichia coli regulates the gene encoding for flavorubredoxin, an enzyme involved in nitrosative detoxification. The present work shows that although purified NorR can bind independently to each of three binding sites in the flavorubredoxin gene promoter, the presence of all sites is required for in vivo nitric oxide-dependent induction of the flavorubredoxin gene. Furthermore, trimerization of NorR upon binding to the three sites was observed by protein cross-linking experiments. These results reveal the importance of the multiple DNA binding sites present on NorR-dependent promoters and suggest that the functional form of NorR is a trimer.
Justino
Marta C
MC
Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa, Apartado 127 Avenida da República, 2781-901 Oeiras, Portugal.
Gonçalves
Vera M M
VM
Saraiva
Lígia M
LM
D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D001665:Binding Sites; D004269:DNA, Bacterial / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D004926:Escherichia coli / Q000201:enzymology* / Q000235:genetics*; D029968:Escherichia coli Proteins / Q000235:genetics / Q000378:metabolism*; D015964:Gene Expression Regulation, Bacterial / Q000502:physiology; D010088:Oxidoreductases / Q000235:genetics / Q000378:metabolism*; D011401:Promoter Regions, Genetic / Q000502:physiology; D011485:Protein Binding; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*; D015533:Transcriptional Activation / Q000502:physiology
D001426:Bacterial Proteins; D004269:DNA, Bacterial; D029968:Escherichia coli Proteins; C474646:NorR protein, Staphylococcus aureus; D014157:Transcription Factors; C451400:YgaK protein, E coli; D010088:Oxidoreductases; C034747:nitric-oxide reductase