The gene encoding the periplasmic cyclophilin homologue, PPIase A, in Escherichia coli, is expressed from four promoters, three of which are activated by the cAMP-CRP complex and negatively regulated by the CytR repressor.
The rot gene in Escherichia coli encodes PPIase A, a periplasmic peptidyl-prolyl cis-trans isomerase with homology to the cyclophilin family of proteins. Here it is demonstrated that rot is expressed in a complex manner from four overlapping promoters and that the rot regulatory region is unusually compact, containing a close array of sites for DNA-binding proteins. The three most upstream rot promoters are activated by the global gene regulatory cAMP-CRP complex and negatively regulated by the CytR repressor protein. Activation of these three promoters occurs by binding of cAMP-CRP to two sites separated by 53 bp. Moreover, one of the cAMP-CRP complexes is involved in the activation of both a Class I and a Class II promoter. Repression takes place by the formation of a CytR/cAMP-CRP/DNA nucleoprotein complex consisting of the two cAMP-CRP molecules and CytR bound in between. The two regulators bind co-operatively to the DNA overlapping the three upstream promoters, simultaneously quenching the cAMP-CRP activator function. These results expand the CytR regulon to include a gene whose product has no known function in ribo- and deoxyribonucleoside catabolism or transport.
Nørregaard-Madsen
M
M
Department of Molecular Biology, Odense University, Denmark.
Mygind
B
B
Pedersen
R
R
Valentin-Hansen
P
P
Søgaard-Andersen
L
L
D000591:Amino Acid Isomerases / Q000235:genetics*; D001426:Bacterial Proteins / Q000378:metabolism; D001483:Base Sequence; D001665:Binding Sites; D002352:Carrier Proteins / Q000235:genetics*; D002874:Chromosome Mapping; D000242:Cyclic AMP / Q000378:metabolism; D002373:Cyclic AMP Receptor Protein / Q000378:metabolism; D017931:DNA Primers / Q000235:genetics; D004269:DNA, Bacterial / Q000235:genetics; D004926:Escherichia coli / Q000201:enzymology* / Q000235:genetics*; D029968:Escherichia coli Proteins; D015964:Gene Expression Regulation, Bacterial; D005798:Genes, Bacterial; D008969:Molecular Sequence Data; D019696:Peptidylprolyl Isomerase; D011401:Promoter Regions, Genetic; D012097:Repressor Proteins / Q000378:metabolism
D001426:Bacterial Proteins; D002352:Carrier Proteins; D002373:Cyclic AMP Receptor Protein; C048425:CytR protein, E coli; D017931:DNA Primers; D004269:DNA, Bacterial; D029968:Escherichia coli Proteins; D012097:Repressor Proteins; D000242:Cyclic AMP; D000591:Amino Acid Isomerases; D019696:Peptidylprolyl Isomerase