PDBsum entry 7ccs

Transport protein

PDB id: 7ccs

Contents

Protein chains

469 a.a.

454 a.a.

PDB id:

7ccs

Name:

Transport protein

Title:

Consensus mutated xct-cd98hc complex

Structure:

4f2 cell-surface antigen heavy chain. Chain: a. Synonym: glycoprotein, 4f2hc,4f2 heavy chain antigen,lymphocyte activation antigen 4f2 large subunit,solute carrier family 3 member 2. Engineered: yes. Consensus mutated anionic amino acid transporter light chain, xc- system. Chain: b.

Source:

Homo sapiens. Human. Organism_taxid: 9606. Gene: slc3a2, mdu1. Expressed in: homo sapiens. Expression_system_taxid: 9606. Expression_system_cell_line: hek293sgnti-. Gene: slc7a11. Expression_system_cell_line: hek293sgnti-

Authors:

K.Oda,Y.Lee,M.Takemoto,K.Yamashita,T.Nishizawa,O.Nureki

Key ref:

K.Oda et al. (2020). Consensus mutagenesis approach improves the thermal stability of system x_c^- transporter, xCT, and enables cryo-EM analyses. Protein Sci, 29, 2398-2407. PubMed id: 33016372 DOI: 10.1002/pro.3966

Date:

17-Jun-20 Release date: 09-Dec-20

Protein chain

P08195  (4F2_HUMAN) -  Amino acid transporter heavy chain SLC3A2 from Homo sapiens

Seq: 630 a.a.

Struc: 469 a.a.

Protein chain

Q9UPY5  (XCT_HUMAN) -  Cystine/glutamate transporter from Homo sapiens

Seq: 501 a.a.

Struc: 454 a.a.*

* PDB and UniProt seqs differ at 98 residue positions (black crosses)

DOI no: 10.1002/pro.3966

Protein Sci 29:2398-2407 (2020)

PubMed id: 33016372

Consensus mutagenesis approach improves the thermal stability of system x_c^- transporter, xCT, and enables cryo-EM analyses.

K.Oda, Y.Lee, P.Wiriyasermkul, Y.Tanaka, M.Takemoto, K.Yamashita, S.Nagamori, T.Nishizawa, O.Nureki.

ABSTRACT

System x_c^- is an amino acid antiporter that imports L-cystine into cells and exports intracellular L-glutamate, at a 1:1 ratio. As L-cystine is an essential precursor for glutathione synthesis, system x_c^- supports tumor cell growth through glutathione-based oxidative stress resistance and is considered as a potential therapeutic target for cancer treatment. System x_c^- consists of two subunits, the light chain subunit SLC7A11 (xCT) and the heavy chain subunit SLC3A2 (also known as CD98hc or 4F2hc), which are linked by a conserved disulfide bridge. Although the recent structures of another SLC7 member, L-type amino acid transporter 1 (LAT1) in complex with CD98hc, have provided the structural basis toward understanding the amino acid transport mechanism, the detailed molecular mechanism of xCT remains unknown. To revealthe molecular mechanism, we performed single-particle analyses of the xCT-CD98hc complex. As wild-type xCT-CD98hc displayed poor stability and could not be purified to homogeneity, we applied a consensus mutagenesis approach to xCT. The consensus mutated construct exhibited increased stability as compared to the wild-type, and enabled the cryoelectron microscopy (cryo-EM) map to be obtained at 6.2 Å resolution by single-particle analysis. The cryo-EM map revealed sufficient electron density to assign secondary structures. In the xCT structure, the hash and arm domains are well resolved, whereas the bundle domain shows some flexibility. CD98hc is positioned next to the xCT transmembrane domain. This study provides the structural basis of xCT, and our consensus-based strategy could represent a good choice toward solving unstable protein structures.