The mycobacterial Mpa-proteasome unfolds and degrades pupylated substrates by engaging Pup's N-terminus
The mycobacterial Mpa-proteasome unfolds and degrades pupylated substrates by engaging Pup's N-terminus
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DOI：
10.1038/emboj.2010.23
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发表时间：
2010-04-07
期刊：
影响因子：
11.4
通讯作者：
Weber-Ban, Eilika
中科院分区：
文献类型：
--
作者：
Striebel, Frank;Hunkeler, Moritz;Weber-Ban, Eilika
结核分枝杆菌和其他放线杆菌一样，除了降解复合体的一般细菌库成员外，还含有蛋白酶体。与真核生物的泛素化类似，底物被原核泛素样蛋白(PUP)标记为蛋白酶体降解，该蛋白由ATPase MPA的N末端卷曲线圈结构域(也称为ARC)识别。在这里，我们重新构建了整个分枝杆菌蛋白酶体降解系统，并建立了关于底物募集、展开和降解的机制特征。我们表明，MPA-蛋白酶体复合体可以展开并降解Pup标记的蛋白质，并且这一活性需要ATPase与蛋白酶体的物理相互作用。此外，我们建立了PUP的N-末端区域作为髓化底物进入MPA孔所需的结构元件。在这个过程中，MPA拉动Pup，启动底物蛋白质的解折叠，并将它们拖向蛋白酶体小室。与真核泛素不同，Pup不是循环利用的，而是随底物一起降解。这为Pup分配了双重功能，既是MPA识别元素，也是线程决定因素。EMBO期刊(2010)29,1262-1271。DOI：10.1038/Intemj.2010.23；2010年3月4日在线发布
Mycobacterium tuberculosis, along with other actinobacteria, harbours proteasomes in addition to members of the general bacterial repertoire of degradation complexes. In analogy to ubiquitination in eukaryotes, substrates are tagged for proteasomal degradation with prokaryotic ubiquitin-like protein (Pup) that is recognized by the N-terminal coiled-coil domain of the ATPase Mpa (also called ARC). Here, we reconstitute the entire mycobacterial proteasome degradation system for pupylated substrates and establish its mechanistic features with respect to substrate recruitment, unfolding and degradation. We show that the Mpa-proteasome complex unfolds and degrades Pup-tagged proteins and that this activity requires physical interaction of the ATPase with the proteasome. Furthermore, we establish the N-terminal region of Pup as the structural element required for engagement of pupylated substrates into the Mpa pore. In this process, Mpa pulls on Pup to initiate unfolding of substrate proteins and to drag them toward the proteasome chamber. Unlike the eukaryotic ubiquitin, Pup is not recycled but degraded with the substrate. This assigns a dual function to Pup as both the Mpa recognition element as well as the threading determinant. The EMBO Journal (2010) 29, 1262-1271. doi:10.1038/emboj.2010.23; Published online 4 March 2010