NtrC (nitrogen regulatory protein C) is a dimeric protein encoded in Escherichia coli that binds to an active amplifier transcription of the glnA gene, which encodes the enzyme glutamine synthetase that catalyzes the synthesis reaction of the amino acid glutamine from of glutamic acid and ammonia. Mechanism of action

The NtrC activating protein is regulated by NtrB protein kinase forming a two-component regulatory system. In response to decreased glutamine in the external environment, NtrB protein kinase phosphorylates residues of the NtrC inducing a conformational change allowing its binding with an amplifier. The phosphorylated NtrC binds to the RNA polymerase bound to the σ factor, located at several base pairs away (linked to the promoter), generating a loop in the DNA. The ATPase activity of the phosphorylated NtrC protein activates the gene transcript by allowing the RNA polymerase to separate the strands of DNA.

"glnA-glutamine synthetase". WikiGenes.

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