Crystallography, Max Delbrück Center for Molecular Medicine, Robert-Rössle Str. 10, 13125 Berlin, Germany; Institute for Chemistry and Biochemistry, Freie Universität Berlin, Takustr. 3, 14195 Berlin, Germany; Department of Molecular Biology, Max-Planck Institute for Infection Biology, Charitéplatz 1, 10117 Berlin, Germany.
Department of Molecular Biology, Max-Planck Institute for Infection Biology, Charitéplatz 1, 10117 Berlin, Germany; Institute of Biotechnology, TIB 4/3-2, Department of Applied Biochemistry, Technical University of Berlin, Gustav-Meyer-Allee 25, 13355 Berlin, Germany.
Cell Rep. 2020 May 19;31(7):107667. doi: 10.1016/j.celrep.2020.107667.
Human guanylate binding protein 1 (hGBP1) belongs to the dynamin superfamily of GTPases and conveys host defense against intracellular bacteria and parasites. During infection, hGBP1 is recruited to pathogen-containing vacuoles, such as Chlamydia trachomatis inclusions, restricts pathogenic growth, and induces the activation of the inflammasome pathway. hGBP1 has a unique catalytic activity to hydrolyze guanosine triphosphate (GTP) to guanosine monophosphate (GMP) in two consecutive cleavage steps. However, the functional significance of this activity in host defense remains elusive. Here, we generate a structure-guided mutant that specifically abrogates GMP production, while maintaining fast cooperative GTP hydrolysis. Complementation experiments in human monocytes/macrophages show that hGBP1-mediated GMP production is dispensable for restricting Chlamydia trachomatis growth but is necessary for inflammasome activation. Mechanistically, GMP is catabolized to uric acid, which in turn activates the NLRP3 inflammasome. Our study demonstrates that the unique enzymology of hGBP1 coordinates bacterial growth restriction and inflammasome signaling.
人类鸟苷酸结合蛋白 1（hGBP1）属于动力蛋白超家族 GTPases，可传递宿主对细胞内细菌和寄生虫的防御。在感染过程中，hGBP1 被招募到含有病原体的小泡中，例如沙眼衣原体包涵体，限制了病原的生长，并诱导了炎症小体途径的激活。hGBP1 具有独特的催化活性，可在两个连续的切割步骤中将鸟苷三磷酸（GTP）水解为鸟苷一磷酸（GMP）。然而，这种活性在宿主防御中的功能意义仍不清楚。在这里，我们生成了一种结构导向的突变体，该突变体特异性地消除了 GMP 的产生，同时保持了快速协同的 GTP 水解。在人单核细胞/巨噬细胞中的补充实验表明，hGBP1 介导的 GMP 产生对于限制沙眼衣原体的生长不是必需的，但对于炎症小体的激活是必需的。从机制上讲，GMP 被分解为尿酸，尿酸反过来又激活 NLRP3 炎症小体。我们的研究表明，hGBP1 的独特酶学特性协调了细菌生长限制和炎症小体信号传导。
