Structural immunology of (super)natural killer cell receptor-ligand recognition

O. Vaněk¹, J. Bláha², B. Kalousková³, O. Skořepa¹, K. Pazderová¹, C. Abreu¹, T. Skálová⁴, J. Dohnálek⁴

¹Department of Biochemistry, Faculty of Science, Charles University, Hlavova 8, 12840 Prague, Czechia

²EMBL, Hamburg Unit c/o DESY, Notkestrasse 85, 22607 Hamburg, Germany

³Institute of Applied Physics – Biophysics group, TU Wien, Getreidemarkt 9, 1060 Vienna, Austria

⁴Institute of Biotechnology of the Czech Academy of Sciences, Průmyslová 595, 25250, Vestec, Czechia

ondrej.vanek@natur.cuni.cz

Natural killer (NK) cells, a subset of effector lymphocytes, are an essential component of non-specific immunity, whose primary function is to recognise and spontaneously destroy damaged, infected, or malignant cells. The cytotoxicity of NK cells is regulated by their surface receptors through which they examine ligands on target cells. Some receptors enhance cytotoxicity (activating receptors), while others suppress it (inhibitory receptors). Which of the signals prevails then determines the action of the NK cell. NK cell cytotoxicity is further modulated by various other stimuli, such as cytokines, and it is executed upon direct cell-to-cell contact with the target cell by a deathly cocktail of enzymes released from lytic granules into the immune synapse. Thus, NK cells promise great therapeutic potential, which is currently being explored using various protein immunotherapeutics and genetically engineered CAR NK cells [1].

Over the last fifteen years, we have contributed to the structural description of various activating and inhibitory NK cell receptors of mouse, rat, and man, as well as of their cognate protein ligands and their mutual complexes. Using a combination of protein X-ray crystallography, small-angle X-ray scattering, and in-solution biophysical methods utilizing individual soluble recombinant proteins, with single-cell localization microscopy techniques observing the proteins expressed on the cell surface, we have become unravelling the almost supernatural nature of NK cell ligand recognition where the usually rather low affinity of single receptor-ligand interaction is overcome by their oligomerization and/or cross-linking/clustering within the immune synapse, thereby deploying avidity instead of affinity [2-4].

1.  O. Vaněk, B. Kalousková, C. Abreu, S. Nejadebrahim, O. Skořepa, Adv. Protein Chem. Struct. Biol., 129, (2022), 91.

2.  O. Vaněk, P. Celadova, O. Skořepa, J. Bláha, B. Kalousková, A. Dvorská, E. Poláchová, H. Pucholtová, D. Kavan, P. Pompach, K. Hofbauerová, V. Kopecký Jr., A. Mesci, S. Voigt, J. R. Carlyle, Sci. Rep., 9,(2019), 17836.

3.  O. Skořepa, S. Pazicky, B. Kalousková, J. Bláha, C. Abreu, T. Ječmen, M. Rosůlek, A. Fish, A. Sedivy, K. Harlos, J. Dohnálek, T. Skálová, O. Vaněk, Cancers, 12, (2020), 1998.

4.  J. Bláha, T. Skálová, B. Kalousková, O. Skořepa, D. Cmunt, V. Grobárová, S. Pazicky, E. Poláchová, C. Abreu, J. Stránský, T. Kovaľ, J. Dušková, Y. Zhao, K. Harlos, J. Hašek, J. Dohnálek, O. Vaněk, Nat. Commun., 13, (2022), 5022.

This research was funded by Czech Science Foundation (18-10687S, 23-08490L), MEYS of the Czech Republic (LTC17065, LTC20078, CZ.02.1.01/0.0/0.0/16_013/0001776), BIOCEV (ERDF CZ.1.05/1.1.00/02.0109), and Charles University (GAUK 927916, 161216, 1378219, 318122). CIISB research infrastructure project LM2015043, funded by MEYS CR, is gratefully acknowledged for the financial support of experiments at the CMS. The authors also acknowledge the support and the use of resources of the Instruct-ERIC and iNEXT infrastructures. K.P. and C.A. received short-term scientific mission support from COST Action CA18103 INNOGLY.