Multiple cis-acting sites positively regulate Escherichia coli nrd expression.
Regulation of nrd expression in Escherichia coli by cis-acting elements was found to be more complex than previously reported. At least five upstream sites appear to positively regulate nrd expression including a Fis binding site, a DnaA binding site, an AT-rich region, an inverted repeat and a 10 bp site between the AT-rich region and the inverted repeat. Double mutants defective in these sites indicate that all sites tested act independently when regulating nrd expression. As the decrease in nrd expression in exponentially growing cultures paralleled the decrease observed in DNA synthesis-inhibited cultures for all single and double mutants, we concluded that nrd is regulated by the same mechanism in these physiological states. As mutants unable to induce nrd expression during inhibition of DNA synthesis also fail to exhibit cell cycle-regulated nrd expression, we conclude that cell cycle nrd regulation is controlled by these same sites. Site-directed mutagenesis was used to show that the absence of an increase in nrd expression during DNA inhibition previously observed for deletion of the AT-rich region results from deletion of both the Fis binding site and the AT-rich region.
Department of Biochemistry, University of Minnesota, St. Paul 55108, USA.
B A
BA
Jacobson
J A
JA
Fuchs
D019677:Artificial Gene Fusion; D001426:Bacterial Proteins / Q000378:metabolism; D001483:Base Sequence; D001665:Binding Sites; D002352:Carrier Proteins / Q000378:metabolism; D004261:DNA Replication; D004268:DNA-Binding Proteins / Q000378:metabolism; D004926:Escherichia coli / Q000201:enzymology / Q000235:genetics*; D029968:Escherichia coli Proteins; D035021:Factor For Inversion Stimulation Protein; D015964:Gene Expression Regulation, Bacterial; D034982:Integration Host Factors; D007763:Lac Operon; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D009154:Mutation; D010957:Plasmids / Q000235:genetics; D011401:Promoter Regions, Genetic; D012045:Regulatory Sequences, Nucleic Acid; D012091:Repetitive Sequences, Nucleic Acid; D012264:Ribonucleotide Reductases / Q000235:genetics* / Q000378:metabolism*; D017384:Sequence Deletion; D013941:Thymine / Q000378:metabolism; D001616:beta-Galactosidase / Q000378:metabolism
D001426:Bacterial Proteins; D002352:Carrier Proteins; D004268:DNA-Binding Proteins; C066312:DnaA protein, Bacteria; D029968:Escherichia coli Proteins; D035021:Factor For Inversion Stimulation Protein; D034982:Integration Host Factors; C440502:integration host factor, E coli; D012264:Ribonucleotide Reductases; D001616:beta-Galactosidase; D013941:Thymine