Structural basis for promoter DNA recognition by the response regulator OmpR

Area of Science:

• Bacterial regulatory mechanisms
• Molecular biology
• Structural biology

Background:

• OmpR is a key response regulator in the EnvZ/OmpR two-component system.
• It controls bacterial porin gene expression (OmpF, OmpC) and virulence.
• The precise DNA binding mechanism and structural basis of OmpR remain unclear.

Purpose of the Study:

• To elucidate the structural basis of OmpR DNA binding.
• To investigate the role of phosphorylation in OmpR DNA interaction.
• To identify potential druggable targets for therapeutic intervention.

Main Methods:

• X-ray crystallography of OmpR DNA-binding domain (OmpRc) complex.
• Nuclear Magnetic Resonance (NMR) spectroscopy.
• Fluorescent polarization and thermal stability assays.

Main Results:

• Crystal structure of OmpRc bound to ompF promoter DNA reveals homodimeric head-to-tail binding.
• OmpRc apo-form exhibits a domain-swapped structure.
• Phosphorylated OmpR shows enhanced DNA binding affinity compared to unphosphorylated OmpR.

Conclusions:

• Phosphorylation enhances OmpR's DNA binding affinity.
• Structural insights into OmpR-DNA interactions offer potential for drug development.
• Understanding OmpR regulation is crucial for bacterial virulence and adaptive responses.