Multidrug Transporter Caught in the Act

Science  23 Dec 2005:
Vol. 310, Issue 5756, pp. 1865a
DOI: 10.1126/science.310.5756.1865a
CREDIT: PORNILLOS ET AL.

Multidrug transporters are integral membrane proteins found in bacteria, which can expel a wide range of drugs and thereby complicate the treatment of a variety of bacterial infections. One such protein, EmrE is a proton-dependent transporter that confers resistance to positively charged hydrophobic antibiotics, including tetracycline. Pornillos et al. (p. 1950) now report the structure of EmrE in complex with a translocation substrate, tetraphenylphosphonium, at 3.7 angstrom resolution. Two EmrE polypeptides form an asymmetric, antiparallel dimer with substrate bound at the dimerization interface. The structure suggests a mechanism in which an asymmetric translocation pathway confers unidirectional transport.

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