Member of the two-component regulatory system PrrB/PrrA that is involved specifically in early intracellular multiplication of Mycobacterium and is essential for its viability (PubMed:11953357, PubMed:22081401). Upon phosphorylation by PrrB, functions as a transcription regulator by direct binding to promoter regions of target genes to positively regulate their expression. Autoregulates its own expression (PubMed:14702417, PubMed:29101285). By nitrogen-limiting conditions. Phosphorylated by PrrB at Asp-58. Also phosphorylated on Thr-6 by PknG/PknK/PknJ. The two phosphorylations act synergistically to activate the DNA-binding activity of PrrA. Extended N-terminus.