Figure 1.

Overlay of (¹H, ¹⁵N)-TROSY HSQC spectra of TPP⁺-bound EmrE in isotropic bicelles reconstituted by different methods. A) ¹⁵N-EmrE in DMPC/DHPC bicelles is better resolved and has better signal/noise when reconstituted through liposomes (red) than when reconstituted through detergent exchange (black). B) The spectral quality of ¹⁵N-EmrE in DMPC/DHPC bicelles degrades with time for EmrE reconstituted via detergent. After nearly two weeks at 45°C, the spectrum (black) has less signal than the initial spectrum (red). C) The spectrum of ²H/¹⁵N/¹³C-EmrE reconstituted into DLPC/DHPC bicelles via liposomes (red) is virtually unchanged after more than six months (black). D) ²H/¹⁵N-EmrE can be stably reconstituted into isotropic bicelles made with different chain lengths (DLPC, blue; DMPC, red; DPPC, black), all capped by DHPC. The minor peak shifts indicate only small changes in EmrE structure with change in bicelle thickness. All spectra were collected at 45°C, in 20 mM KPi, 20 mM NaCl, 30 mM sodium cacodylate, pH 7.