Physiological involvement in pH signaling of Vps24-mediated recruitment of Aspergillus PalB cysteine protease to ESCRT-III.
Physiological involvement in pH signaling of Vps24-mediated recruitment of Aspergillus PalB cysteine protease to ESCRT-III.
复制标题
DOI：
10.1074/jbc.m808645200
复制
发表时间：
2009-02-13
期刊：
影响因子：
--
通讯作者：
Peñalva MA
中科院分区：
文献类型：
--
作者：
Rodríguez-Galán O;Galindo A;Hervás-Aguilar A;Arst HN Jr;Peñalva MA
构巢曲霉转录因子 PacC 的激活涉及其环境 pH 依赖性 C 端蛋白水解作用，PacC 介导基因表达的环境 pH 调节，并由 Vps32 相互作用支架 PalA 招募至 ESCRT-III。该反应几乎肯定是由 PalB 钙蛋白酶样蛋白酶催化的。在这里，我们表明 PalB 与膜结合，并与 ESCRT-III Vps24 特异性且直接地相互作用。 PalB N 端 MIT 结构域和 Vps24 C 端 MIM 基序对于这种相互作用是必要且充分的。 PalBΔMIT 是一种缺乏 MIT 结构域的突变 PalB，无法有效地募集到膜上，并且 PacC 蛋白水解过程受到损害。值得注意的是，通过将 Vps24 共价连接到突变体 PalBΔMIT，促进了膜募集并且很大程度上恢复了 PacC 处理。这是第一个报道的证据，证明类钙蛋白酶招募至 ESCRT-III 晶格发挥着生理作用。它明确地将钙蛋白酶样蛋白酶 PalB 定位在 ESCRT-III 相关 pH 信号复合物中，强调了 ESCRT-III 在环境 pH 信号转导中的积极作用，并提出了 PalB 激活的可能机制。
Activation of the Aspergillus nidulans transcription factor PacC, which mediates ambient pH regulation of gene expression and is recruited to ESCRT-III by the Vps32-interacting scaffold PalA, involves its ambient pH-dependent C-terminal proteolysis. This reaction is almost certainly catalyzed by the PalB calpain-like protease. Here we show that PalB associates with membranes and interacts specifically and directly with ESCRT-III Vps24. The PalB N-terminal MIT domain and the Vps24 C-terminal MIM motif are necessary and sufficient for this interaction. PalBΔMIT, a mutant PalB lacking the MIT domain is inefficiently recruited to membranes and impaired in PacC proteolytic processing. Notably, membrane recruitment is promoted and PacC processing largely restored by covalent attachment of Vps24 to mutant PalBΔMIT. This is the first reported evidence that calpain-like recruitment to ESCRT-III lattices plays a physiological role. It unambiguously positions the calpain-like protease PalB within the ESCRT-III-associated pH signaling complex, underlines the positive role of ESCRT-III in ambient pH signal transduction, and suggests a possible mechanism for PalB activation.