Functional Analysis of Hsp33-a Redox Regulated Chaperone

描述（由申请人提供）：在过去几年中，在理解氧化应激及其对蛋白质等大分子的影响方面取得了良好进展。氧化修饰的蛋白质已被证明在衰老、癌症和许多其他病理条件下积累。这进一步增加了人们对压力情况的兴趣，这种情况对于生活在厌氧生活方式中的生物体来说是不可避免的。现在，已经鉴定了许多蛋白质，它们使用氧化应激作为其功能活性的调节剂。这些蛋白质共同具有高度反应性的半胱氨酸，其感测环境的氧化还原电位的变化并将其转化为蛋白质构象和活性的变化。我们发现这些新的氧化还原调节蛋白质之一是分子伴侣Hsp33。热休克蛋白33是一种折叠辅助蛋白，似乎专门保护细胞免受氧化应激的致命影响。现在我们将分析Hsp33如何执行此任务。我们将确定伴随热休克蛋白33的激活和失活过程的构象重排，我们将确定底物识别的潜在机制。我们将定义热休克蛋白33的底物是在热和氧化应激条件下。这将不仅使我们能够识别和分类的氧化敏感蛋白的保护Hsp33，但也可以解释如何Hsp33的底物特异性不同于其他分子伴侣。我们将探讨热休克蛋白33提出的一些底物蛋白的细胞的蛋白水解系统的可能性。已知许多氧化修饰的蛋白质被不可逆地损伤，并且在它们可以在细胞中积累为有害的不溶性蛋白质聚集体之前需要被降解。由于Hsp33对蛋白质折叠中间体具有非常高的亲和力，这种底物转移到细胞蛋白酶也可以解释为什么Hsp33的伴侣活性需要在非应激条件下下调。否则，Hsp33具有通过过早地将折叠蛋白呈递给细胞的蛋白水解系统而干扰正常蛋白质折叠过程的潜力。

DESCRIPTION (provided by applicant): Over the past few years, good progress has been made in understanding oxidative stress and its consequences for macromolecules such as proteins. Oxidatively modified proteins have been shown to accumulate during aging, cancer and many other pathological conditions. This has further increased the interest in a stress situation that is simply unavoidable for organisms that live an anaerobic lifestyle. Now, a number of proteins have been identified which use oxidative stress as a regulator for their functional activity. These proteins have in common highly reactive cysteines that sense the changes in the redox potential of the environment and translate them into changes of protein conformation and activity. We discovered that one of these novel redox regulated proteins is the molecular chaperone Hsp33. Hsp33 is a folding-helper protein that appears to be specialized to protect cells against the otherwise lethal effects of oxidative stress. We will now analyze how Hsp33 performs this task. We will identify the conformational rearrangements that accompany the activation and inactivation process of Hsp33 and we will determine the underlying mechanism of substrate recognition. We will define what Hsp33's substrates are under heat and oxidative stress conditions. This will not only allow us to identify and classify oxidation sensitive proteins which are protected by Hsp33 but may also explain how Hsp33's substrate specificity differs from that of other molecular chaperones. We will explore the possibility that Hsp33 presents some of its substrate proteins to the proteolytic system of the cell. It is known that many oxidatively modified proteins are irreversibly damaged and need to be degraded before they can accumulate as harmful, insoluble protein aggregates in the cell. Since Hsp33 has a very high affinity to protein folding intermediates, this substrate transfer to cellular proteases might also explain why Hsp33's chaperone activity needs to be down regulated under non stress conditions. Otherwise, Hsp33 has the potential of interfering with ,the normal protein folding process by prematurely presenting folding proteins to the proteolytic system of the cell.