Discipline of Pharmacology, School of Medical Sciences, Faculty of Medicine and Health and Sydney Nano, University of Sydney, Sydney, NSW, Australia.
EMBL Australia Node in Single Molecule Sciences, School of Medical Science, University of New South Wales, Sydney, NSW, Australia.
EMBO Rep. 2019 Feb;20(2). doi: 10.15252/embr.201846518. Epub 2018 Nov 29.
The murine cytomegalovirus protein M45 protects infected mouse cells from necroptotic death and, when heterologously expressed, can protect human cells from necroptosis induced by tumour necrosis factor receptor (TNFR) activation. Here, we show that the N-terminal 90 residues of the M45 protein, which contain a RIP homotypic interaction motif (RHIM), are sufficient to confer protection against TNFR-induced necroptosis. This N-terminal region of M45 drives rapid self-assembly into homo-oligomeric amyloid fibrils and interacts with the RHIMs of the human kinases RIPK1 and RIPK3, and the Z-DNA binding protein 1 (ZBP1), to form heteromeric amyloid fibrils Mutation of the tetrad residues in the M45 RHIM attenuates homo- and hetero-amyloid assembly by M45, suggesting that the amyloidogenic nature of the M45 RHIM underlies its biological activity. The M45 RHIM preferentially interacts with RIPK3 and ZBP1 over RIPK1 and alters the properties of the host RHIM protein assemblies. Our results indicate that M45 mimics the interactions made by RIPK1 or ZBP1 with RIPK3, thereby forming heteromeric amyloid structures, which may explain its ability to inhibit necroptosis.
鼠巨细胞病毒蛋白 M45 可保护感染的小鼠细胞免于发生坏死性细胞死亡，并且当异源表达时，可保护人类细胞免于肿瘤坏死因子受体 (TNFR) 激活诱导的坏死性细胞死亡。在这里，我们表明，M45 蛋白的 N 端 90 个残基（包含 RIP 同源相互作用基序 (RHIM)）足以赋予对 TNFR 诱导的坏死性细胞死亡的保护作用。M45 的该 N 端区域可快速自组装成同型寡聚体淀粉样纤维，并与人类激酶 RIPK1 和 RIPK3 的 RHIM 以及 Z-DNA 结合蛋白 1 (ZBP1) 相互作用，形成异源淀粉样纤维。M45 RHIM 中四联体残基的突变削弱了 M45 的同型和异型淀粉样纤维组装，表明 M45 RHIM 的淀粉样纤维形成性质是其生物学活性的基础。M45 RHIM 优先与 RIPK3 和 ZBP1 相互作用，而不是与 RIPK1 相互作用，并改变宿主 RHIM 蛋白组装的性质。我们的结果表明，M45 模拟了 RIPK1 或 ZBP1 与 RIPK3 的相互作用，从而形成异源淀粉样结构，这可能解释了其抑制坏死性细胞死亡的能力。
