The mitochondrial serine protease High-temperature requirement A2 (HtrA2) is associated with various diseases including neurodegenerative disorders and cancer. Despite availability of structural details, the reports on HtrA2’s mechanistic regulation that varies with the type of activation signals still remain non-concordant. To expound the role of regulatory PDZ (Postsynaptic density-95/Discs large/Zonula occludens-1) domains in multimodal activation of HtrA2, we generated heterotrimeric HtrA2 variants comprising different numbers of PDZs and/or active-site mutations. Sequential deletion of PDZs from the trimeric ensemble significantly affected its residual activity in a way that proffered a hypothesis advocating inter-molecular allosteric crosstalk via PDZs in HtrA2. Furthermore, structural and computational snapshots affirmed the role of PDZs in secondary structural element formation around the regulatory loops and coordinated reorganization of the N-terminal region. Therefore, apart from providing cues for devising structure-guided therapeutic strategies, this study establishes a physiologically relevant working model of complex allosteric regulation through a trans-mediated cooperatively shared energy landscape.

线粒体丝氨酸蛋白酶高温需求 A2 (HtrA2) 与多种疾病有关，包括神经退行性疾病和癌症。尽管可获得结构细节，但关于随激活信号类型变化的 HtrA2 机械调节的报告仍然不一致。为了阐明调节性 PDZ（突触后密度-95/Discs large/Zonula occludens-1）结构域在 HtrA2 的多模式激活中的作用，我们生成了包含不同数量的 PDZ 和/或活性位点突变的异源三聚体 HtrA2 变体。从三聚体集合中连续删除 PDZ 显着影响其残留活性，从而提出了一种假设，即通过 HtrA2 中的 PDZ 进行分子间变构串扰。此外，结构和计算快照证实了 PDZ 在调节环周围的二级结构元件形成和 N 末端区域的协调重组中的作用。因此，除了为设计结构指导的治疗策略提供线索外，本研究还通过跨中介合作共享能源格局。