General
From the article: "The critical role of DNA in the equilibrium between OmpR and phosphorylated OmpR mediated by
EnvZ in Escherichiacoli"
- Low medium osmolarity, the cellular OmpR-P level is reduced as the ratio of EnvZ kinase to phosphatase activity decreases, transcription of ompF
- Domain A serves as a phosphatase for OmpR-P
- OmpR-P binds to -100 to -39 region of ompF.
- Sequestration of OmpR-P from the dephosphorylation reaction by its binding to DNA. Inhibited slightly by the adition of F1-F2-F3, increason the half-life of OmpR-P to 65 min.
- F1 or C1 was capable of binding to OmpR-P independently but not all the other sites.
- OmpR-P binds to the 380 to 361 region (F4 site), the 100 to 39 region (F1, F2, and F3 sites) of ompF, and the 100 to 38 region (C1, C2, and C3 sites) of ompC.
- C-terminal binding domain
- Four reactions occour simultaneosly: autophosphorylation, phosphotransfer, autophosphatase and phosphatase. OmpR mainly exists as unphosphorylated, strong phosphatase activity.
- OmpR-p autophosphatase activity with a half-life of 56 min.
- In the presence of Mg2+ and cofactor ADP, EnvZc displays a strong phosphatase activity, reducing the half-life to less than 30 sec.
- Phosphatase reaction is affected by OmpR-P-specific DNA.
- E. coli contains OmpR at the level of 10^3 molecules per cell.
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