Structural Determinants of Herpesvirus Entry Mediator Recognition by Murine B and T Lymphocyte Attenuator
| Autor: | John R. Sedy, Paula S. Norris, Marcel D. Fremont, Daved H. Fremont, Carl F. Ware, Kenneth M. Murphy, Christopher A. Nelson |
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| Rok vydání: | 2008 |
| Předmět: |
Herpesvirus entry mediator
Protein Conformation T cell DNA Mutational Analysis Molecular Sequence Data Immunology Attenuator (genetics) BTLA Biology Crystallography X-Ray Mice Dogs Immune system Protein Interaction Mapping medicine Animals Humans Immunology and Allergy Amino Acid Sequence Receptors Immunologic Surface plasmon resonance Conserved Sequence T lymphocyte Surface Plasmon Resonance Virology Rats Cell biology medicine.anatomical_structure Amino Acid Substitution Ectodomain Receptors Tumor Necrosis Factor Member 14 |
| Zdroj: | The Journal of Immunology. 180:940-947 |
| ISSN: | 1550-6606 0022-1767 |
| DOI: | 10.4049/jimmunol.180.2.940 |
| Popis: | The B and T lymphocyte attenuator (BTLA) appears to act as a negative regulator of T cell activation and growth. BTLA specifically interacts with herpesvirus entry mediator (HVEM), a member of the TNFR family. Herein, we have undertaken surface plasmon resonance studies to quantitatively assess BTLA and HVEM ectodomain interactions. We find that soluble BALB/cJ BTLA engages HVEM with an equilibrium affinity of 0.97 ± 0.19 μM while the C57BL/6 BTLA binds slightly better with an equilibrium affinity of 0.42 ± 0.06 μM. Despite its lower affinity for HVEM, the kinetic half-life of BALB/cJ BTLA complexes are twice as long as observed for C57BL/6 BTLA (4 vs 2 s). To further explore these interactions, we solved the crystal structure of a murine BTLA (BALB/cJ) ectodomain at 1.8-Å resolution, revealing a β sandwich fold with strong similarity to I-set members of the Ig superfamily. Using a structure-based mutagenesis strategy, we then examined the individual contributions of 26 BTLA surface-exposed residues toward HVEM binding. Four single-site substitutions were identified that decrease HVEM binding below detectable levels and two that decrease binding by more than half. All six of these cluster at the edge of the β sandwich in a membrane distal patch formed primarily from the A and G strands. This patch falls within the contacting surface recently revealed in the crystal structure of the human BTLA-HVEM cocomplex. The critical binding residues identified here are highly conserved across species, suggesting that BTLA employs a conserved binding mode for HVEM recognition. |
| Databáze: | OpenAIRE |
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