D55Q-T83A and D55Q-G94S, two pseudorevertants of the D55Q mutant OmpR, an Escherichia coli transcriptional activator, were isolated previously by R. Brissette, K. Tsung, and M. Inouye (J. Bacteriol. 173:3749-3755, 1991). These pseudorevertant OmpR proteins were purified and examined for their function as transcriptional activators in a cell-free system with an ompF DNA fragment. These proteins were transcriptionally active, even after acid treatment, whereas the wild-type OmpR was completely inactive after the same treatment. Phosphorylation of acid-treated wild-type OmpR with an EnvZ11 membrane fraction and ATP restored transcriptional activity, whereas the activities of the mutant OmpR proteins did not change after phosphorylation.
All Science Journal Classification (ASJC) codes
- Molecular Biology