PDBsum entry 6y2h

Transport protein

PDB id: 6y2h

Contents

Protein chains

223 a.a.

211 a.a.

Ligands

SCN ×13

Waters ×381

PDB id:

6y2h

Name:

Transport protein

Title:

The crystal structure of human chloride intracellular channel protein 5

Structure:

Chloride intracellular channel protein 5. Chain: a, b, c, d. Engineered: yes

Source:

Homo sapiens. Human. Organism_taxid: 9606. Gene: clic5. Expressed in: escherichia coli. Expression_system_taxid: 562

Resolution:

2.15Å R-factor: 0.203 R-free: 0.244

Authors:

A.Ferofontov,M.Giladi,Y.Haitin

Key ref:

A.Ferofontov et al. (2020). Conserved cysteine dioxidation enhances membrane interaction of human Cl^- intracellular channel 5. FASEB J, 34, 9925-9940. PubMed id: 32725932 DOI: 10.1096/fj.202000399R

Date:

16-Feb-20 Release date: 20-May-20

Protein chains

Q9NZA1  (CLIC5_HUMAN) -  Chloride intracellular channel protein 5 from Homo sapiens

Seq: 410 a.a.

Struc: 223 a.a.*

Protein chain

Q9NZA1  (CLIC5_HUMAN) -  Chloride intracellular channel protein 5 from Homo sapiens

Seq: 410 a.a.

Struc: 211 a.a.*

* PDB and UniProt seqs differ at 7 residue positions (black crosses)

Enzyme reactions

• Enzyme class: Chains A, B, C, D: E.C.1.8.-.-

DOI no: 10.1096/fj.202000399R

FASEB J 34:9925-9940 (2020)

PubMed id: 32725932

Conserved cysteine dioxidation enhances membrane interaction of human Cl^- intracellular channel 5.

A.Ferofontov, P.Vankova, P.Man, M.Giladi, Y.Haitin.

ABSTRACT

The human chloride intracellular channel (hCLIC) family is thought to transition between globular and membrane-associated forms by exposure of a hydrophobic surface. However, the molecular identity of this surface, and the triggering events leading to its exposure, remain elusive. Here, by combining biochemical and structural approaches, together with mass spectrometry (MS) analyses, we show that hCLIC5 is inherently flexible. X-ray crystallography revealed the existence of a globular conformation, while small-angle X-ray scattering showed additional elongated forms consisting of exposure of the conserved hydrophobic inter-domain interface to the bulk phase. Tryptophan fluorescence measurements demonstrated that the transition to the membrane-associated form is enhanced by the presence of oxidative environment and lipids. Using MS, we identified a dose-dependent oxidation of a highly conserved cysteine residue, known to play a key role in the structurally related omega-class of glutathione-S-transferases. Hydrogen/deuterium exchange MS analysis revealed that oxidation of this cysteine facilitates the exposure of the conserved hydrophobic inter-domain interface. Together, our results pinpoint an oxidation of a specific cysteine residue as a triggering mechanism initializing the molecular commitment for membrane interaction in the CLIC family.