Structural and Biophysical Insights into the TCRαβ Complex in Chickens

Lijie Zhang; Yanjie Liu; Geng Meng; Ruiying Liang; Bing Zhang; Chun Xia

doi:10.1016/j.isci.2020.101828

Structural and Biophysical Insights into the TCRαβ Complex in Chickens

iScience. 2020 Nov 20;23(12):101828. doi: 10.1016/j.isci.2020.101828. eCollection 2020 Dec 18.

Authors

Lijie Zhang^{1

2}, Yanjie Liu¹, Geng Meng¹, Ruiying Liang¹, Bing Zhang¹, Chun Xia¹

Affiliations

¹ Department of Microbiology and Immunology, College of Veterinary Medicine, China Agricultural University, Haidian District, Beijing 100193, China.
² Joint National Laboratory for Antibody Drug Engineering, Key Laboratory of Cell and Molecular Immunology, School of Medical Sciences, Henan University, Kaifeng 475004, China.

Abstract

In this work, chicken HPAIV H5N1 epitope-specific TCRαβ (ch-TCRαβ) was isolated and its structure was determined. The Cα domain of ch-TCRαβ does not exhibit the typical structure of human TCRαβ, and the DE loop extends outward, resulting in close proximity between the Cα domain of ch-TCRαβ and CD3εδ/γ. The FG loop of the Cβ domain of ch-TCRαβ is shorter. The changes in the C domains of ch-TCRαβ and the difference in chicken CD3εδ/γ confirm that the complexes formed by TCRαβ and CD3εδ/γ differ from those in humans. In the chicken complex, a positively charged cleft is formed between the two CDR3 loops that might accommodate the acidic side chains of the chicken pMHC-I-bound HPAIV epitope intermediate portion oriented toward ch-TCRαβ. This is the first reported structure of chicken TCRαβ, and it provides a structural model of the ancestral TCR system in the immune synapses between T cells and antigen-presenting cells in lower vertebrates.

Keywords: Immunology; Structural Biology.