Quantitative time-resolved analysis reveals intricate, differential regulation of standard- and immuno-proteasomes.
Quantitative time-resolved analysis reveals intricate, differential regulation of standard- and immuno-proteasomes.
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DOI：
10.7554/elife.07545
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发表时间：
2015-09-22
期刊：
影响因子：
7.7
通讯作者：
Mishto M
中科院分区：
文献类型：
--
作者：
Liepe J;Holzhütter HG;Bellavista E;Kloetzel PM;Stumpf MP;Mishto M
蛋白酶体蛋白降解是蛋白质半衰期的关键决定因素，因此也决定了从基本代谢到一系列免疫过程的细胞过程。尽管它很重要，但调节蛋白酶体活性的机制还不完全清楚。在这里，我们使用迭代和紧密结合的实验和建模方法来开发、探索和验证蛋白酶体肽水解动力学的机制模型。20S蛋白酶体是一种动态酶，由于底物和产物以及蛋白水解和调节位点之间的相互作用，其活性随时间而变化；该模型预测了这些位点的位置和它们之间的相互作用，并得到了实验支持。分析表明，水解的限速步骤是底物进入蛋白酶体的运输。人体标准蛋白酶体和免疫蛋白酶体之间的转运效率不同，因此影响到总降解率和底物切割位点的使用。DOI: http://dx.doi.org/10.7554/eLife.07545.001细胞必须能够可靠地破坏或移除它们内部不再需要的分子。蛋白酶体的结构在这个复杂的过程中起着核心作用，通过切割和消化蛋白质。哺乳动物有几种不同类型的蛋白酶体，每种蛋白酶体都由几种蛋白质“亚基”组成。例如，当细胞经历炎症时，一些蛋白酶体改变它们的一些亚基，形成免疫蛋白酶体。这些免疫蛋白酶体往往比“标准”蛋白酶体更快地分解蛋白质，但目前尚不清楚它们是如何做到这一点的。Liepe等人现在将实验和数学建模相结合，构建了蛋白酶体活性的详细模型。该模型表明，蛋白质进出蛋白酶体腔室是限制蛋白酶体分解蛋白质速度的步骤。此外，这些转运过程在很大程度上也导致了标准蛋白酶体和免疫蛋白酶体加工蛋白质的不同速率。Liepe等人也证实了蛋白酶体中存在调控位点，并描述了它们是如何排列的。改变蛋白酶体分解蛋白质速度的问题与肿瘤、神经系统疾病和自身免疫性疾病有关。Liepe等人的模型开启了研究蛋白酶体活性如何受药物影响的能力，因此更容易研究以治疗为目的干扰蛋白酶体活性的方法。DOI: http://dx.doi.org/10.7554/eLife.07545.002
Proteasomal protein degradation is a key determinant of protein half-life and hence of cellular processes ranging from basic metabolism to a host of immunological processes. Despite its importance the mechanisms regulating proteasome activity are only incompletely understood. Here we use an iterative and tightly integrated experimental and modelling approach to develop, explore and validate mechanistic models of proteasomal peptide-hydrolysis dynamics. The 20S proteasome is a dynamic enzyme and its activity varies over time because of interactions between substrates and products and the proteolytic and regulatory sites; the locations of these sites and the interactions between them are predicted by the model, and experimentally supported. The analysis suggests that the rate-limiting step of hydrolysis is the transport of the substrates into the proteasome. The transport efficiency varies between human standard- and immuno-proteasomes thereby impinging upon total degradation rate and substrate cleavage-site usage. DOI: http://dx.doi.org/10.7554/eLife.07545.001 Cells have to be able to reliably destroy or remove molecules from their interior that they no longer need. Structures called proteasomes play a central part in this complex process by cutting up and digesting proteins. Mammals have several different types of proteasomes, each made up of several protein ‘subunits’. For example, when a cell experiences inflammation some proteasomes change some of their subunits and form an immuno-proteasome. These immuno-proteasomes tend to break down proteins more quickly than ‘standard’ proteasomes, but it was not clear how they are able to do so. Liepe et al. have now combined experiments and mathematical modelling to construct a detailed model of proteasome activity. The model shows that protein transport into and out of the proteasome chamber are the steps that limit how quickly the proteasomes can break down proteins. Furthermore, these transport processes are also to a large extent responsible for the different rates at which standard and immuno-proteasomes process proteins. Liepe et al. were also able to confirm the existence of regulatory sites within the proteasome, and describe how these are arranged. Problems that alter the rate at which proteasomes break down proteins have been linked to tumors and neurological and autoimmune diseases. Liepe et al.'s model opens up the ability to study how the proteasome's activity is affected by drugs and therefore makes it easier to investigate ways of interfering with this activity for therapeutic purposes. DOI: http://dx.doi.org/10.7554/eLife.07545.002