Small Multidrug Resistance Efflux Pumps

Abstract

Small multidrug resistance (SMR) transporters confer resistance to a variety of quaternary cation compound antimicrobials. These secondary active transporters are the smallest known transporters and have been demonstrated to function within the membrane. The focus of this chapter explores and updates SMR family diversity and reviews current structural and functional knowledge of these members. This chapter also provides an update of known SMR pump-mediated resistance to antimicrobial substrates (including naturally synthesized quaternary cation compounds) and their clinical significance.