7AIO image
Entry Detail
PDB ID:
7AIO
EMDB ID:
Title:
Structure of Human Potassium Chloride Transporter KCC3 S45D/T940D/T997D in NaCl (Subclass)
Biological Source:
Source Organism:
Host Organism:
PDB Version:
Deposition Date:
2020-09-28
Release Date:
2021-06-02
Method Details:
Experimental Method:
Resolution:
3.31 Å
Aggregation State:
PARTICLE
Reconstruction Method:
SINGLE PARTICLE
Macromolecular Entities
Polymer Type:polypeptide(L)
Description:Solute carrier family 12 member 6
Chain IDs:A (auth: B), B (auth: A)
Chain Length:1099
Number of Molecules:2
Biological Source:Homo sapiens
Ligand Molecules
Primary Citation

Abstact

Potassium-coupled chloride transporters (KCCs) play crucial roles in regulating cell volume and intracellular chloride concentration. They are characteristically inhibited under isotonic conditions via phospho-regulatory sites located within the cytoplasmic termini. Decreased inhibitory phosphorylation in response to hypotonic cell swelling stimulates transport activity, and dysfunction of this regulatory process has been associated with various human diseases. Here, we present cryo-EM structures of human KCC3b and KCC1, revealing structural determinants for phospho-regulation in both N- and C-termini. We show that phospho-mimetic KCC3b is arrested in an inward-facing state in which intracellular ion access is blocked by extensive contacts with the N-terminus. In another mutant with increased isotonic transport activity, KCC1Δ19, this interdomain interaction is absent, likely due to a unique phospho-regulatory site in the KCC1 N-terminus. Furthermore, we map additional phosphorylation sites as well as a previously unknown ATP/ADP-binding pocket in the large C-terminal domain and show enhanced thermal stabilization of other CCCs by adenine nucleotides. These findings provide fundamentally new insights into the complex regulation of KCCs and may unlock innovative strategies for drug development.

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Disease

Primary Citation of related structures