Activation of the MprBA two-component system in Mycobacterium smegmatis under acidic and respiration-inhibitory conditions and crosstalk between MprA and KdpD.

Activation of the MprBA two-component system in Mycobacterium smegmatis is strongest under acidic pH, with MprA-dependent sigE expression being notably elevated.

• Why it matters: Understanding how mycobacteria respond to environmental stresses like acidity and respiratory inhibition is crucial for insights into their persistence and pathogenicity, especially in host conditions.
• What they did: Researchers used genetic inactivation, chemical inhibitors, hypoxia, and pH variation to demonstrate MprBA pathway activation, and identified KdpD as an alternative kinase activating MprA in the absence of MprB.
• The result: Findings reveal that MprA can be phosphorylated by KdpD without MprB, and that the MprBA-SigE-SigB pathway is essential for optimal growth under acidic stress, highlighting its role in mycobacterial survival.