Control of PP1/PP2A Activity With Small Molecule Toxins

用小分子毒素控制 PP1/PP2A 活性

• 批准号: 7030245
• 负责人: A RICHARD CHAMBERLIN
• 金额: $ 26.49万
• 依托单位: UNIVERSITY OF CALIFORNIA-IRVINE
• 依托单位国家: 美国
• 财政年份: 1998
• 资助国家: 美国
• 起止时间: 1998-08-01 至 2008-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7030245
• 关键词: X ray crystallography; allosteric site; antineoplastics; biological products; biological signal transduction; calcineurin; chimeric proteins; combinatorial chemistry; cytotoxicity; drug design /synthesis /production; enzyme activity; enzyme structure; molecular site; okadaic acid; peptide library; phosphatase inhibitor; protein binding; protein tyrosine phosphatase; small molecule

DESCRIPTION (provided by applicant): The structurally diverse group of natural toxins including okadaic acid, calyculin, microcystin LR, and tautomycin exert their cytotoxic effects by inhibiting the serine-threonine protein phosphatases PP1 and PP2A. This activity dramatically increases the phosphorylation state of a variety of proteins within the cell, which in turn results in acute toxic effects or unregulated cellular proliferation. The compounds themselves are therefore not only hepatotoxins, but also tumor promoters. Because as a group they inhibit PP1 and PP2A quite potently and specifically relative to other known phosphatases such as PP2B (calcineurin), PP2C, and the tyrosine phosphatases, several members of this group have become important PP1/2A structural/activity probes and, more generally, tools for studying intracellular signaling pathways. However, there is still a demand for new inhibitors with increased selectivity or other desirable properties such as improved membrane permeability. A very recent report that the naturally occurring toxin tautomycetin inhibits PP1 an order of magnitude more selectively (40:1) than tautomycin provides an important new lead in this endeavor. In addition, at about the same time, the structure of the okadaic acid-PP1 complex was published, providing for the first time solid structural information about this inhibitor that will allow us to design analogs that are much more synthetically accessible than okadaic acid itself. While most of the studies in this field have focused on the active sites of PP1 and PP2A, in the past several years some attention has shifted to characterizing an allosteric site on these phosphatases that modulates activity by interacting with a variety of binding (regulatory) proteins. Although small peptide analogues of the regulatory protein binding domains are known to bind to the regulatory site of PP1, there have been no reports of small molecule ligands for the regulatory site. We will therefore prepare libraries of small molecule/peptide hybrids and study their interactions with the regulatory site, opening the door to the design and synthesis of non-protein PP1 activators. Supporting this new area, as well as our ongoing inhibitor design program, we will conduct enzymological and structural studies in collaboration with a prominent X-ray crystallographer, Professor Tom Poulos, in order to obtain detailed structural information concerning the hypotheses upon which our designs are based.

描述（由申请人提供）：结构上多样化的天然毒素组，包括冈田酸，钙化蛋白，微囊蛋白酶LR和六霉素，通过抑制丝氨酸 - 硫代硫代蛋白蛋白磷酸酶PP1和PP2A发挥其细胞毒性作用。该活性大大增加了细胞内各种蛋白质的磷酸化状态，这反过来又导致急性毒性作用或不调节的细胞增殖。因此，化合物本身不仅是肝毒素，而且是肿瘤启动子。 因为作为一个小组，它们相对于其他已知的磷酸酶（例如PP2B（钙调神经酶），PP2C和酪氨酸磷酸酶）的抑制非常有效，特别是相对于其他已知的磷酸酶的抑制，因此该组的几个成员已成为重要的PP1/2A结构/活性探针，并且更普遍地研究了胞内信号通道的工具。但是，仍然需要对具有提高选择性或其他理想特性（例如改善膜渗透性）的新抑制剂的需求。最近的一份报告是，自然存在的毒素六霉素抑制PP1比六霉素更有选择地（40：1）抑制PP1的数量级（40：1），这在这项工作中为新的领先优势提供了重要的新领先优势。此外，大约在同一时间，发表了冈田酸-PP1复合物的结构，这是有关该抑制剂的首次实心结构信息，这将使我们能够设计出比Okadaic Acid本身更容易访问的类似物。 尽管该领域的大多数研究都集中在PP1和PP2A的活性位点上，但在过去的几年中，一些注意力转移到了这些磷酸酶上的变构位点的表征，这些磷酸酶通过与多种结合（调节）蛋白质相互作用来调节活性。尽管已知调节蛋白结合结构域的小肽类似物与PP1的调节位点结合，但没有针对调节位点的小分子配体的报道。因此，我们将准备小分子/肽杂种的文库，并研究其与调节位点的相互作用，为非蛋白质PP1激活剂的设计和合成打开了大门。支持这个新领域以及我们正在进行的抑制剂设计计划，我们将与著名的X射线晶体学家Tom Poulos教授合作进行酶学和结构研究，以获取有关我们设计所基于的假设的详细结构信息。