title: Crystal structure of cell adhesion molecule nectin-2/CD112 and its binding to immune receptor DNAM-1/CD226.
abstract: The nectin and nectin-like molecule (Necl) family includes important cell adhesion molecules (CAMs) characterized by their Ig-like nature. Such CAMs regulate a broad spectrum of cell-cell interactions, including the interaction between NK cells and cytotoxic T lymphocytes (CTLs) and their target cells. CAM members nectin-2 (CD112) and Necl-5 (CD155) are believed to form homodimers (for nectin-2) or heterodimers in their functions for cell adhesion, as well as to interact with immune costimulatory receptor DNAX accessory molecule 1 (DNAM-1) (CD226) to regulate functions of both NK and CTL cells. However, the structural basis of the interactive mode of DNAM-1 with nectin-2 or Necl-5 is not yet understood. In this study, a soluble nectin-2 Ig-like V-set domain (nectin-2v) was successfully prepared and demonstrated to bind to both soluble ectodomain and cell surface-expressed full-length DNAM-1. The 1.85-Å crystal structure of nectin-2v displays a perpendicular homodimer arrangement, revealing the homodimer characteristics of the nectin and Necls. Further mutational analysis indicated that disruption of the homodimeric interface of nectin-2v led to a failure of the homodimer formation, as confirmed by crystal structure and biochemical properties of the mutant protein of nectin-2v. Interestingly, the monomer mutant also loses DNAM-1 binding, as evidenced by cell staining with tetramers and surface plasmon resonance assays. The data indicate that interaction with DNAM-1 requires either the homodimerization or engagement of the homodimeric interface of nectin-2v. These results have implications for immune intervention of tumors or autoimmune diseases in the DNAM-1/nectin-2-dependent pathway.
authors.affiliation: CAS Key Laboratory of Pathogenic Microbiology and Immunology, Institute of Microbiology, Chinese Academy of Sciences, Beijing, 100101 China.
authors.forename: Jun
authors.initials: J
authors.lastname: Liu
authors.forename: Xiaomin
authors.initials: X
authors.lastname: Qian
authors.forename: Zhujun
authors.initials: Z
authors.lastname: Chen
authors.forename: Xiang
authors.initials: X
authors.lastname: Xu
authors.forename: Feng
authors.initials: F
authors.lastname: Gao
authors.forename: Shuijun
authors.initials: S
authors.lastname: Zhang
authors.forename: Rongguang
authors.initials: R
authors.lastname: Zhang
authors.forename: Jianxun
authors.initials: J
authors.lastname: Qi
authors.forename: George F
authors.initials: GF
authors.lastname: Gao
authors.forename: Jinghua
authors.initials: J
authors.lastname: Yan
mesh_terms: D000818:Animals; D000945:Antigens, Differentiation, T-Lymphocyte / Q000096:biosynthesis / Q000737:chemistry* / Q000378:metabolism*; D015815:Cell Adhesion Molecules / Q000737:chemistry* / Q000378:metabolism*; D018360:Crystallography, X-Ray; D006801:Humans; D057927:Hydrophobic and Hydrophilic Interactions; D007135:Immunoglobulin Variable Region / Q000737:chemistry / Q000378:metabolism; D051379:Mice; D000075983:Nectins; D011485:Protein Binding / Q000276:immunology; D055503:Protein Multimerization / Q000276:immunology; D017434:Protein Structure, Tertiary; D000098862:T Lineage-Specific Activation Antigen 1
chemical_list: D000945:Antigens, Differentiation, T-Lymphocyte; D000098862:T Lineage-Specific Activation Antigen 1; D015815:Cell Adhesion Molecules; D007135:Immunoglobulin Variable Region; D000075983:Nectins