A combined biochemical and cellular approach reveals Zn2+-dependent hetero- and homodimeric CD4 and Lck assemblies in T cells

Anna M Kocyła; Aleksander Czogalla; Inga Wessels; Lothar Rink; Artur Krężel

doi:10.1016/j.str.2023.11.013

A combined biochemical and cellular approach reveals Zn²⁺-dependent hetero- and homodimeric CD4 and Lck assemblies in T cells

Structure. 2024 Mar 7;32(3):292-303.e7. doi: 10.1016/j.str.2023.11.013. Epub 2023 Dec 28.

Authors

Anna M Kocyła¹, Aleksander Czogalla², Inga Wessels³, Lothar Rink³, Artur Krężel⁴

Affiliations

¹ Department of Chemical Biology, Faculty of Biotechnology, University of Wroclaw, 50-383 Wroclaw, Poland.
² Department of Cytobiochemistry, Faculty of Biotechnology, University of Wroclaw, 50-383 Wroclaw, Poland.
³ Institute of Immunology, Faculty of Medicine, RWTH Aachen University, 52074 Aachen, Germany.
⁴ Department of Chemical Biology, Faculty of Biotechnology, University of Wroclaw, 50-383 Wroclaw, Poland. Electronic address: artur.krezel@uwr.edu.pl.

PMID: 38157858
DOI: 10.1016/j.str.2023.11.013

Abstract

The CD4 or CD8 co-receptors' interaction with the protein-tyrosine kinase Lck initiates the tyrosine phosphorylation cascade leading to T cell activation. A critical question is: to what extent are co-receptors and Lck coupled? Our contribution concerns Zn²⁺, indispensable for CD4^- and CD8-Lck formation. We combined biochemical and cellular approaches to show that dynamic fluctuations of free Zn²⁺ in physiological ranges influence Zn(CD4)₂ and Zn(CD4)(Lck) species formation and their ratio, although the same Zn(Cys)₂(Cys)₂ cores. Moreover, we demonstrated that the affinity of Zn²⁺ to CD4 and CD4-Lck species differs significantly. Increased intracellular free Zn²⁺ concentration in T cells causes higher CD4 partitioning in the plasma membrane. We additionally found that CD4 palmitoylation decreases the specificity of CD4-Lck formation in the reconstituted membrane model. Our findings help elucidate co-receptor-Lck coupling stoichiometry and demonstrate that intracellular free Zn²⁺ has a major role in the interplay between CD4 dimers and CD4-Lck assembly.

Keywords: free zinc; interprotein zinc binding site; receptor clustering; zinc clasp domain; zinc regulation.

MeSH terms

CD4 Antigens
Lymphocyte Specific Protein Tyrosine Kinase p56(lck)* / metabolism
Phosphorylation
Receptors, Antigen, T-Cell
Signal Transduction
T-Lymphocytes* / metabolism
Zinc / metabolism

Substances

Lymphocyte Specific Protein Tyrosine Kinase p56(lck)
CD4 Antigens
Zinc
Receptors, Antigen, T-Cell