Member of the two-component regulatory system PilS/PilR that regulates the expression of multiple genes including the type IV pilus (T4P) major subunit PilA (PubMed:8097014, PubMed:7911557). Thereby, plays a major role in the regulation of multiple motility pathways (PubMed:30042200). Upon appropriate environmental signals, the histidine kinase PilS transfers the phosphoryl group onto PilR (PubMed:8097014). In turn, PilR functions as a transcriptional activator by direct binding to a cis-acting sequence upstream of the pilin gene promoter leading to its activation (PubMed:1317379, PubMed:7715443). Phosphorylated by PilS. Deletion mutant results in changes in swimming, swarming and/or twitching motility associated with virulence in specific hosts.