Turner Madison, Uday Adwaith B, Velyvis Algirdas, Rennella Enrico, Zeytuni Natalie, Vahidi Siavash
Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario, Canada.
Department of Anatomy and Cell Biology, McGill University, Montréal, QC, Canada.
Nat Commun. 2025 Apr 1;16(1):3138. doi: 10.1038/s41467-025-58430-0.
The Mycobacterium tuberculosis (Mtb) proteasome system selectively degrades damaged or misfolded proteins and is crucial for the pathogen's survival within the host. Targeting the 20S core particle (CP) offers a viable strategy for developing tuberculosis treatments. The activity of Mtb 20S CP, like that of its eukaryotic counterpart, is allosterically regulated, yet the specific conformations involved have not been captured in high-resolution structures to date. Here, we use single-particle electron cryomicroscopy and H/D exchange mass spectrometry to determine the Mtb 20S CP structure in an auto-inhibited state that is distinguished from the canonical resting state by the conformation of switch helices at the α/β interface. The rearrangement of these helices collapses the S1 pocket, effectively inhibiting substrate binding. Biochemical experiments show that the Mtb 20S CP activity can be altered through allosteric sites far from the active site. Our findings underscore the potential of targeting allostery to develop antituberculosis therapeutics.
结核分枝杆菌（Mtb）蛋白酶体系统可选择性降解受损或错误折叠的蛋白质，对该病原体在宿主体内的存活至关重要。靶向20S核心颗粒（CP）为开发结核病治疗方法提供了一种可行策略。Mtb 20S CP的活性与其真核对应物一样，受到别构调节，但迄今为止，尚未通过高分辨率结构捕捉到所涉及的具体构象。在这里，我们使用单颗粒冷冻电子显微镜和氢/氘交换质谱法来确定处于自抑制状态的Mtb 20S CP结构，该状态通过α/β界面处开关螺旋的构象与典型的静止状态区分开来。这些螺旋的重排使S1口袋塌陷，有效抑制底物结合。生化实验表明，Mtb 20S CP的活性可以通过远离活性位点的别构位点来改变。我们的研究结果强调了靶向别构作用开发抗结核治疗药物的潜力。
