A two-component system MechNtrB/MechNtrC related to nitrogen metabolism regulation in Micromonospora echinospora DSM43816

The NtrB/NtrC two-component signal transduction system (TCS), predominantly found in Gram-negative bacteria, plays a crucial role in nitrogen metabolism regulation. Through BLASTP analysis of the complete proteome of <i>Micromonospora echinospora</i> DSM 43816 against the NtrB/NtrC database, homologous proteins were identified and designated as MechNtrB and MechNtrC. Subsequent <i>in vitro</i> expression and phosphorylation assays demonstrated that both proteins undergo phosphorylation, indicating a phosphoryl transfer mechanism for signal transduction between them. Yeast two-hybrid (Y2H) screening using selective media further verified specific <i>in vivo</i> protein-protein interactions between MechNtrB and MechNtrC. Quantitative real-time PCR (RT-qPCR) analyses revealed that overexpression of <i>MechNtrB</i> or <i>MechNtrC</i> gene significantly modulated the expression levels of key nitrogen metabolism genes, including those encoding glutamine synthetase (GS), glutamate synthase (GOGAT), and glutamate dehydrogenase (GDH). These collective findings establish that MechNtrB/MechNtrC constitutes a functional TCS in <i>M. echinospora</i> that directly regulates bacterial nitrogen metabolism.