regulates protein(s) and two-component regulatory system modulating antibiotic efflux leuO antibiotic_resistance ARO:3003843 leuO, a LysR family transcription factor, exists in a wide variety of bacteria of the family Enterobacteriaceae and is involved in the regulation of as yet unidentified genes affecting the stress response and pathogenesis expression. LeuO is also an activator of the MdtNOP efflux pump. leuO MdtNOP