Referenced in: none

Automatically associated channels: HCN2

Title: Structural basis for gating mechanisms of a eukaryotic P-glycoprotein homolog.

Authors: Atsushi Kodan, Tomohiro Yamaguchi, Toru Nakatsu, Keita Sakiyama, Christopher J Hipolito, Akane Fujioka, Ryo Hirokane, Keiji Ikeguchi, Bunta Watanabe, Jun Hiratake, Yasuhisa Kimura, Hiroaki Suga, Kazumitsu Ueda, Hiroaki Kato

Journal, date & volume: Proc. Natl. Acad. Sci. U.S.A., 2014 Mar 18 , 111, 4049-54

PubMed link: http://www.ncbi.nlm.nih.gov/pubmed/24591620

Abstract
P-glycoprotein is an ATP-binding cassette multidrug transporter that actively transports chemically diverse substrates across the lipid bilayer. The precise molecular mechanism underlying transport is not fully understood. Here, we present crystal structures of a eukaryotic P-glycoprotein homolog, CmABCB1 from Cyanidioschyzon merolae, in two forms: unbound at 2.6-Å resolution and bound to a unique allosteric inhibitor at 2.4-Å resolution. The inhibitor clamps the transmembrane helices from the outside, fixing the CmABCB1 structure in an inward-open conformation similar to the unbound structure, confirming that an outward-opening motion is required for ATP hydrolysis cycle. These structures, along with site-directed mutagenesis and transporter activity measurements, reveal the detailed architecture of the transporter, including a gate that opens to extracellular side and two gates that open to intramembranous region and the cytosolic side. We propose that the motion of the nucleotide-binding domain drives those gating apparatuses via two short intracellular helices, IH1 and IH2, and two transmembrane helices, TM2 and TM5.