Genentech, Inc., 1 DNA Way, South San Francisco, CA, 94080, USA.
Gilead Sciences, Inc., 333 Lakeside Drive, Foster City, CA, 94404, USA.
Nat Commun. 2024 May 2;15(1):3725. doi: 10.1038/s41467-024-48014-9.
Hematopoietic progenitor kinase 1 (HPK1) is a negative regulator of T-cell receptor signaling and as such is an attractive target for cancer immunotherapy. Although the role of the HPK1 kinase domain (KD) has been extensively characterized, the function of its citron homology domain (CHD) remains elusive. Through a combination of structural, biochemical, and mechanistic studies, we characterize the structure-function of CHD in relationship to KD. Crystallography and hydrogen-deuterium exchange mass spectrometry reveal that CHD adopts a seven-bladed β-propellor fold that binds to KD. Mutagenesis associated with binding and functional studies show a direct correlation between domain-domain interaction and negative regulation of kinase activity. We further demonstrate that the CHD provides stability to HPK1 protein in cells as well as contributes to the docking of its substrate SLP76. Altogether, this study highlights the importance of the CHD in the direct and indirect regulation of HPK1 function.
造血祖细胞激酶 1（HPK1）是 T 细胞受体信号的负调节剂，因此是癌症免疫治疗的一个有吸引力的靶点。尽管 HPK1 激酶结构域（KD）的作用已被广泛研究，但它的柠檬酸同源结构域（CHD）的功能仍不清楚。通过结构、生化和机制研究的结合，我们描述了 CHD 与 KD 相关的结构-功能关系。晶体学和氘氢交换质谱揭示了 CHD 采用七叶β-推进器折叠结构，与 KD 结合。与结合和功能研究相关的突变显示，结构域-结构域相互作用与激酶活性的负调节之间存在直接相关性。我们进一步证明，CHD 不仅为 HPK1 蛋白在细胞内提供稳定性，还为其底物 SLP76 的对接做出贡献。总的来说，这项研究强调了 CHD 在 HPK1 功能的直接和间接调节中的重要性。
