Key Findings

A single amino acid difference in the PmrA transcription factor from S. paratyphi B compared to S. typhimurium leads to differential dependence on the PmrD protein for polymyxin B resistance. The pmrA(E211) allele exhibits reduced DNA binding affinity and requires PmrD for effective gene expression, while the pmrA(G211) allele functions independently of PmrD.