title: The structure of the atypical killer cell immunoglobulin-like receptor, KIR2DL4.
abstract: The engagement of natural killer cell immunoglobulin-like receptors (KIRs) with their target ligands, human leukocyte antigen (HLA) molecules, is a critical component of innate immunity. Structurally, KIRs typically have either two (D1-D2) or three (D0-D1-D2) extracellular immunoglobulin domains, with the D1 and D2 domain recognizing the α1 and α2 helices of HLA, respectively, whereas the D0 domain of the KIR3DLs binds a loop region flanking the α1 helix of the HLA molecule. KIR2DL4 is distinct from other KIRs (except KIR2DL5) in that it does not contain a D1 domain and instead has a D0-D2 arrangement. Functionally, KIR2DL4 is also atypical in that, unlike all other KIRs, KIR2DL4 has both activating and inhibitory signaling domains. Here, we determined the 2.8 Å crystal structure of the extracellular domains of KIR2DL4. Structurally, KIR2DL4 is reminiscent of other KIR2DL receptors, with the D0 and D2 adopting the C2-type immunoglobulin fold arranged with an acute elbow angle. However, KIR2DL4 self-associated via the D0 domain in a concentration-dependent manner and was observed as a tetramer in the crystal lattice by size exclusion chromatography, dynamic light scattering, analytical ultracentrifugation, and small angle x-ray scattering experiments. The assignment of residues in the D0 domain to forming the KIR2DL4 tetramer precludes an interaction with HLA akin to that observed for KIR3DL1. Accordingly, no interaction was observed to HLA by direct binding studies. Our data suggest that the unique functional properties of KIR2DL4 may be mediated by self-association of the receptor.
authors.affiliation: From the Department of Biochemistry and Molecular Biology, School of Biomedical Sciences, and.
authors.forename: Shoeib
authors.initials: S
authors.lastname: Moradi
authors.affiliation: From the Department of Biochemistry and Molecular Biology, School of Biomedical Sciences, and the Australian Research Council Centre of Excellence for Advanced Molecular Imaging, Monash University, Clayton, Victoria 3800, Australia.
authors.forename: Richard
authors.initials: R
authors.lastname: Berry
authors.affiliation: From the Department of Biochemistry and Molecular Biology, School of Biomedical Sciences, and.
authors.forename: Phillip
authors.initials: P
authors.lastname: Pymm
authors.affiliation: From the Department of Biochemistry and Molecular Biology, School of Biomedical Sciences, and.
authors.forename: Corinne
authors.initials: C
authors.lastname: Hitchen
authors.affiliation: From the Department of Biochemistry and Molecular Biology, School of Biomedical Sciences, and.
authors.forename: Simone A
authors.initials: SA
authors.lastname: Beckham
authors.affiliation: From the Department of Biochemistry and Molecular Biology, School of Biomedical Sciences, and.
authors.forename: Matthew C J
authors.initials: MC
authors.lastname: Wilce
authors.affiliation: From the Department of Biochemistry and Molecular Biology, School of Biomedical Sciences, and.
authors.forename: Nicholas G
authors.initials: NG
authors.lastname: Walpole
authors.affiliation: From the Department of Biochemistry and Molecular Biology, School of Biomedical Sciences, and.
authors.forename: Craig S
authors.initials: CS
authors.lastname: Clements
authors.affiliation: From the Department of Biochemistry and Molecular Biology, School of Biomedical Sciences, and.
authors.forename: Hugh H
authors.initials: HH
authors.lastname: Reid
authors.affiliation: the Department of Biochemistry, La Trobe Institute for Molecular Science, La Trobe University, Melbourne Victoria 3086 Australia.
authors.forename: Matthew A
authors.initials: MA
authors.lastname: Perugini
authors.affiliation: the Department of Microbiology and Immunology, Peter Doherty Institute for Infection and Immunity, University of Melbourne, Parkville, Victoria 3010, Australia, and.
authors.forename: Andrew G
authors.initials: AG
authors.lastname: Brooks
authors.affiliation: From the Department of Biochemistry and Molecular Biology, School of Biomedical Sciences, and the Australian Research Council Centre of Excellence for Advanced Molecular Imaging, Monash University, Clayton, Victoria 3800, Australia, the Institute of Infection and Immunity, Cardiff University, School of Medicine, Heath Park, Cardiff CF14 4XN, United Kingdom Jamie.rossjohn@monash.edu.
authors.forename: Jamie
authors.initials: J
authors.lastname: Rossjohn
authors.affiliation: From the Department of Biochemistry and Molecular Biology, School of Biomedical Sciences, and the Australian Research Council Centre of Excellence for Advanced Molecular Imaging, Monash University, Clayton, Victoria 3800, Australia, Julian.vivian@monash.edu.
authors.forename: Julian P
authors.initials: JP
authors.lastname: Vivian
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D016367:Baculoviridae / Q000235:genetics / Q000378:metabolism; D003001:Cloning, Molecular; D018360:Crystallography, X-Ray; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D015870:Gene Expression; D015235:HLA-B Antigens / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D059951:HLA-G Antigens / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009036:Moths / Q000166:cytology / Q000378:metabolism; D055503:Protein Multimerization; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D054345:Receptors, KIR2DL4 / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D016415:Sequence Alignment
chemical_list: D015235:HLA-B Antigens; C484830:HLA-B*57:01 antigen; D059951:HLA-G Antigens; C515079:KIR2DL4 protein, human; D054345:Receptors, KIR2DL4; D011994:Recombinant Proteins
keywords: Immunoglobulin Fold; Natural Killer Cells (NK Cells); Protein Structure; Receptor Structure-Function; Small Angle X-ray Scattering (SAXS)