Download MendeleyStructure of the human cation-chloride cotransport KCC1 in an outward-open state.
Zhao, Y., Shen, J., Wang, Q., Ruiz Munevar, M.J., Vidossich, P., De Vivo, M., Zhou, M., Cao, E.(2022) Proc Natl Acad Sci U S A 119: e2109083119-e2109083119
- PubMed: 35759661
- DOI: https://doi.org/10.1073/pnas.2109083119
- Primary Citation of Related Structures:
7TTH, 7TTI - PubMed Abstract:
Cation-chloride cotransporters (CCCs) catalyze electroneutral symport of Cl - with Na + and/or K + across membranes. CCCs are fundamental in cell volume homeostasis, transepithelia ion movement, maintenance of intracellular Cl - concentration, and neuronal excitability. Here, we present a cryoelectron microscopy structure of human K + -Cl - cotransporter (KCC)1 bound with the VU0463271 inhibitor in an outward-open state. In contrast to many other amino acid-polyamine-organocation transporter cousins, our first outward-open CCC structure reveals that opening the KCC1 extracellular ion permeation path does not involve hinge-bending motions of the transmembrane (TM) 1 and TM6 half-helices. Instead, rocking of TM3 and TM8, together with displacements of TM4, TM9, and a conserved intracellular loop 1 helix, underlie alternate opening and closing of extracellular and cytoplasmic vestibules. We show that KCC1 intriguingly exists in one of two distinct dimeric states via different intersubunit interfaces. Our studies provide a blueprint for understanding the mechanisms of CCCs and their inhibition by small molecule compounds.
Organizational Affiliation:
Department of Biochemistry, University of Utah School of Medicine, Salt Lake City, UT 84112.
