Member of the two-component regulatory system ArsS/ArsR that regulates genes involved in biofilm formation and acid adaptation by acting on major ammonia-producing pathways (PubMed:16672598, PubMed:22865848, PubMed:27432830). 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 ArsR (PubMed:10735847). In turn, ArsR binds to the upstream promoter regions of target genes including ureA, amiE and amiF to positively regulate their expression in response to acidic pH (PubMed:15109719, PubMed:16672598). Participates also in acidic acclimatation in a phosphorylation-independent pathway by regulating acid-induced trafficking of urease and its accessory proteins to the inner membrane (PubMed:25997502). ATP + protein L-histidine = ADP + protein N-phospho-L-histidine. Autophosphorylated. Deletion leads to a decreased urease activity to one-third of the level of the wild type (PubMed:22865848). Displays also an exacerbated stress response that results in enhanced and accelerated biofilm formation (PubMed:27432830). The gene was originally annotated as two separate ORFs HP_0165 (AC O24972) and HP_0164 (AC O24971) probably due to a sequencing error.