The activity of the ribonucleotide monophosphatase UmpH is controlled by interaction with the GlnK signaling protein in Escherichia coli.

The PII signaling proteins are ubiquitous in prokaryotes serving as crucial metabolic hubs in different metabolic pathways because of their ability to sense and integrate signals of the cellular nitrogen, carbon, and energy levels. In this study, we used ligand fishing assays to identify the ribonucleotide monophosphatase UmpH enzyme as a novel target of the PII signaling protein GlnK in Escherichia coli. In vitro analyses showed that UmpH interacts specifically with the PII protein GlnK but not with its paralog protein GlnB.