TY - JOUR
T1 - Cryo-EM structure of the human NKCC1 transporter reveals mechanisms of ion coupling and specificity
AU - Neumann, Caroline
AU - Rosenbaek, Lena Lindtoft
AU - Flygaard, Rasmus Kock
AU - Habeck, Michael
AU - Karlsen, Jesper Lykkegaard
AU - Wang, Yong
AU - Lindorff-Larsen, Kresten
AU - Gad, Hans Henrik
AU - Hartmann, Rune
AU - Lyons, Joseph Anthony
AU - Fenton, Robert A
AU - Nissen, Poul
N1 - ©2022 The Authors. Published under the terms of the CC BY NC ND 4.0 license.
PY - 2022/12
Y1 - 2022/12
N2 - The sodium-potassium-chloride transporter NKCC1 of the SLC12 family performs Na
+ -dependent Cl
- - and K
+ -ion uptake across plasma membranes. NKCC1 is important for regulating cell volume, hearing, blood pressure, and regulation of hyperpolarizing GABAergic and glycinergic signaling in the central nervous system. Here, we present a 2.6 Å resolution cryo-electron microscopy structure of human NKCC1 in the substrate-loaded (Na
+ , K
+ , and 2 Cl
- ) and occluded, inward-facing state that has also been observed for the SLC6-type transporters MhsT and LeuT. Cl
- binding at the Cl1 site together with the nearby K
+ ion provides a crucial bridge between the LeuT-fold scaffold and bundle domains. Cl
- -ion binding at the Cl2 site seems to undertake a structural role similar to conserved glutamate of SLC6 transporters and may allow for Cl
- -sensitive regulation of transport. Supported by functional studies in mammalian cells and computational simulations, we describe a putative Na
+ release pathway along transmembrane helix 5 coupled to the Cl2 site. The results provide insight into the structure-function relationship of NKCC1 with broader implications for other SLC12 family members.
AB - The sodium-potassium-chloride transporter NKCC1 of the SLC12 family performs Na
+ -dependent Cl
- - and K
+ -ion uptake across plasma membranes. NKCC1 is important for regulating cell volume, hearing, blood pressure, and regulation of hyperpolarizing GABAergic and glycinergic signaling in the central nervous system. Here, we present a 2.6 Å resolution cryo-electron microscopy structure of human NKCC1 in the substrate-loaded (Na
+ , K
+ , and 2 Cl
- ) and occluded, inward-facing state that has also been observed for the SLC6-type transporters MhsT and LeuT. Cl
- binding at the Cl1 site together with the nearby K
+ ion provides a crucial bridge between the LeuT-fold scaffold and bundle domains. Cl
- -ion binding at the Cl2 site seems to undertake a structural role similar to conserved glutamate of SLC6 transporters and may allow for Cl
- -sensitive regulation of transport. Supported by functional studies in mammalian cells and computational simulations, we describe a putative Na
+ release pathway along transmembrane helix 5 coupled to the Cl2 site. The results provide insight into the structure-function relationship of NKCC1 with broader implications for other SLC12 family members.
KW - Humans
KW - Cryoelectron Microscopy
KW - Potassium/metabolism
KW - Sodium/metabolism
KW - Solute Carrier Family 12, Member 2/genetics
KW - chloride transport
KW - cation:chloride cotransporters
KW - ion sites
KW - NKCC1
KW - ion coupling
U2 - 10.15252/embj.2021110169
DO - 10.15252/embj.2021110169
M3 - Journal article
C2 - 36239040
SN - 0261-4189
VL - 41
JO - The EMBO Journal
JF - The EMBO Journal
IS - 23
M1 - e110169
ER -