Member of the two-component regulatory system BasS/BasR. BasR induces the transcription of the ugd, ais, arnBCADTEF and eptA-basRS loci, all involved in resistance to polymyxin (By similarity). Homodimer. The eptA-basRS operon is positively autoregulated by BasR under high iron or aluminum concentration conditions. Phosphorylated by BasS. The activity of the BasR protein is in some natural isolates, but not in strain K12, controlled at a post-transcriptional level by the PmrD protein under low Mg(2+) concentration conditions.