Role of sequence bias in the topology of the multidrug transporter EmrE.

Authors

McHaourab HS Hassane S , Mishra S Sanjay , Koteiche HA Hanane A , Amadi SH Sepan H .
Biochemistry. 2008 8 5; 47(31).
7980-2

Abstract

EmrE is the prototype of small multidrug resistance transporters and has emerged as a model of membrane protein evolution. Analysis of the distances separating symmetry-related site-specific spin labels, correlation of topological sequence bias to C-terminal orientation, to membrane insertion efficiency, and to resistance to ethidium bromide collectively demonstrate that EmrE monomers adopt a parallel topology in the functional dimer. We propose a coupled insertion and assembly model for EmrE in which the favorable energetics of the parallel dimer interface override topological constraints arising from weak asymmetry in positive charge distribution.