Role of phosphorylated metabolic intermediates in the regulation of glutamine synthetase synthesis in Escherichia coli.

摘要: Transcription of the Ntr regulon is controlled by two-component system consisting response regulator NRI (NtrC) and kinase/phosphatase NRII (NtrB), which both phosphorylates dephosphorylates NRI. Even though in vitro transcription from nitrogen-regulated promoters requires phosphorylated NRI, NRII-independent activation also occurs vivo. We show here that this likely involves acetyl phosphate; it eliminated mutations reduce synthesis phosphate elevated a mutation expected to cause accumulation phosphate. With purified components, we investigated mechanism stimulates glutamine synthetase synthesis. Acetyl phosphate, carbamyl phosphoramidate but not ATP or phosphoenolpyruvate acted as substrates for autophosphorylation vitro. Phosphorylated produced exhibited properties associated with NRII, including activated ATPase activity central domain ability activate glnAp2 promoter.