The stalk domain and the glycosylation status of the activating natural killer cell receptor NKp30 are important for ligand binding.
The natural cytotoxicity receptors are a unique set of activating proteins expressed mainly on the surface of natural killer (NK) cells. The human natural cytotoxicity receptor family comprises the three type I membrane proteins NKp30, NKp44, and NKp46. Especially NKp30 is critical for the cytotoxicity of NK cells against different targets including tumor, virus-infected, and immature dendritic cells. Although the crystal structure of NKp30 was recently solved (Li, Y., Wang, Q., and Mariuzza, R. A. (2011) J. Exp. Med. 208, 703-714; Joyce, M. G., Tran, P., Zhuravleva, M. A., Jaw, J., Colonna, M., and Sun, P. D. (2011) Proc. Natl. Acad. Sci. U.S.A. 108, 6223-6228), a key question, how NKp30 recognizes several non-related ligands, remains unclear. Therefore, we investigated the parameters that impact ligand recognition of NKp30. Based on various NKp30-hIgG1-Fc fusion proteins, which were optimized for minimal background binding to cellular Fcγ receptors, we identified the flexible stalk region of NKp30 as an important but so far neglected module for ligand recognition and related signaling of the corresponding full-length receptor proteins. Moreover, we found that the ectodomain of NKp30 is N-linked glycosylated at three different sites. Mutational analyses revealed differential binding affinities and signaling capacities of mono-, di-, or triglycosylated NKp30, suggesting that the degree of glycosylation could provide a switch to modulate the ligand binding properties of NKp30 and NK cell cytotoxicity.
Georg-Speyer-Haus, Institute of Biomedical Research, D-60596 Frankfurt am Main, Germany.
Jessica
J
Hartmann
Thuy-Van
TV
Tran
Janina
J
Kaudeer
Karin
K
Oberle
Julia
J
Herrmann
Isabell
I
Quagliano
Tobias
T
Abel
André
A
Cohnen
Volker
V
Gatterdam
Andrea
A
Jacobs
Bernd
B
Wollscheid
Robert
R
Tampé
Carsten
C
Watzl
Andreas
A
Diefenbach
Joachim
J
Koch
D000818:Animals; D016466:CHO Cells; D019556:COS Cells; D002522:Chlorocebus aethiops; D006224:Cricetinae; D003412:Cricetulus; D006031:Glycosylation; D057809:HEK293 Cells; D006801:Humans; D007111:Immunity, Cellular / Q000502:physiology; D020014:K562 Cells; D007694:Killer Cells, Natural / Q000166:cytology / Q000276:immunology / Q000473:pathology*; D009154:Mutation; D055628:Natural Cytotoxicity Triggering Receptor 3 / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D009844:Oligosaccharides / Q000235:genetics / Q000378:metabolism; D017434:Protein Structure, Tertiary / Q000502:physiology; D017452:Receptors, IgG / Q000235:genetics / Q000378:metabolism
C431710:NCR3 protein, human; D055628:Natural Cytotoxicity Triggering Receptor 3; D009844:Oligosaccharides; D017452:Receptors, IgG