Atypical OmpR/PhoB subfamily response regulator glnr of actinomycetes functions as a homodimer, stabilized by the unphosphorylated conserved Asp-focused charge interactions

Background: Orphan response transcription factor GlnR regulates nitrogen metabolism in important actinomycetes. Results: GlnR has no typical "phosphorylation pocket," where the only conserved Asp is unphosphorylated but is essential for functional homodimerization. Conclusion: Actinomycete GlnR is an atypical response regulator functioning as a homodimer. Significance: Conserved Asp-focused charge interactions of actinomycete GlnR are probably the mechanism that stabilizes the homodimer for physiological function.