In vivo regulation of the Escherichia coli araC promoter

Abstract

The ara p(C) promoter is known to be derepressed about fivefold for 20 to 30 min after the addition of arabinose. This transient derepression was studied by using araC::Mu lac insertions and araC-lacZ gene fusions. In strains containing increased levels of araC protein, the p(C) promoter became progressively less derepressible, but the ara p(BAD) promoter remained normally inducible. Repression of p(C) was reestablished 20 min after induction in araB mutants, but did not occur in arabinose-transport-deficient mutants. Finally, mutant araC(c) proteins which normally do not repress p(C) did so in the presence of arabinose.