Member of the two-component regulatory system MprB/MprA which contributes to maintaining a balance among several systems involved in stress resistance and is required for establishment and maintenance of persistent infection in the host. In response to environmental signals MprB acts as both a membrane-associated protein kinase that undergoes autophosphorylation and subsequently transfers the phosphate to MprA, and a protein phosphatase that dephosphorylates phospho-MprA (By similarity). MprB/MprA up-regulates expression of mprA and pepD. ATP + protein L-histidine = ADP + protein N-phospho-L-histidine. Induced by MprA. Induced by low concentrations of sodium dodecyl sulfate (SDS). In strain BCG / Pasteur, induced during growth in macrophages. Autophosphorylated.