DNA REPAIR SIGNALING BY NOVEL POLYUBIQUITIN CHAINS

描述（由申请人提供）： 通过Ub-K63连接的多聚泛素（polyUb）链在保守的RAD 6 DNA损伤耐受途径中充当非蛋白水解信号，而通过Ub-K48连接的链发挥不同的作用，充当蛋白酶体蛋白水解的信号。这些和其他观察结果表明，组装成不同类型的polyUb链的Ub是一种机制，赋予功能多样性的信号转导泛素。K63- 1连接的polyUb链在DNA损伤耐受中的信号传递是从酵母到人类的保守信号，但尽管最近的进展，这种新信号的分子功能仍然知之甚少。拟议的研究通过涉及生物化学和分子遗传学方法的机械集中的方法来解决这个问题。具体目标是1）阐明K63- 1连接的polyUb链的DNA损伤信号传导的特定机制（目标1-3）和2）发现许多蛋白质中存在的小Ub结合元件（乌巴结构域;目标4）的连接特异性链识别的基础原理。我们的研究结果可能揭示癌症和其他由基因组不稳定性引起的疾病的原因。我们的研究结果也可能提示抑制RAD 6通路的方法，这可能在化疗或放射增敏中具有临床益处。最后，我们的分子探索（聚）Ub识别的乌巴结构域应有助于建立基本的信号识别原则，并可能导致更好地欣赏信号的多样性和特异性的泛素。

DESCRIPTION (provided by applicant): Polyubiquitin (polyUb) chains linked through Ub-K63 act as a non-proteolytic signal in the conserved RAD6 DNA damage tolerance pathway, while chains linked through Ub-K48 play a different role, acting as a signal for proteasome proteolysis. These and other observations suggest that the assembly of Ub into different types of polyUb chains is a mechanism for imparting functional diversity in signaling by ubiquitin. Signaling by K63-1inked polyUb chains in DNA damage tolerance is conserved from yeast to man. But despite recent advances, the molecular function of this novel signal remains poorly understood. The proposed research targets this question through mechanistically focused approaches involving biochemical and molecular genetic methods. The specific goals are 1) to elucidate the specific mechanism of DNA damage signaling by K63-1inked polyUb chains (Aims 1-3) and 2) to discover the principles that underlie linkage-specific chain recognition by a small Ub-binding element that occurs in numerous proteins (the UBA domain; Aim 4). The results of our studies may shed light on the causes of cancer and other diseases promoted by genomic instability. Our findings may also suggest ways to inhibit the RAD6 pathway, which could be clinically beneficial in chemotherapy or radiosensitization. Finally, our molecular exploration of (poly)Ub recognition by UBA domains should help to establish fundamental signal recognition principles and may lead to a better appreciation of diversity and specificity in signaling by ubiquitin.