Member of the two-component regulatory system NarS/NarL involved in gene expression during aerobic nitrate metabolism (PubMed:25659431). Plays therefore a crucial role in anaerobic survival of mycobacteria in host. Functions as a sensor protein kinase which is autophosphorylated at a histidine residue and transfers its phosphate group to the conserved aspartic acid residue in the regulatory domain of NarL (PubMed:25659431). In turn, NarL binds to the upstream promoter regions of target genes to regulate their expression during aerobic nitrate metabolism (PubMed:25659431). ATP + protein L-histidine = ADP + protein N-phospho-L-histidine. Autophosphorylated on His-241.