Identifying the roles of DNA rewinding enzymes on maintaining genome stability

 描述(申请人提供)：我们的遗传物质的结构和完整性具有重要的生物学意义。DNA是一个动态的分子，识别和表征改变DNA结构的酶是必不可少的。DNA解旋酶是一种由ATP驱动的马达蛋白，可以解开DNA，并帮助将单链DNA结合蛋白(如RPA)加载到DNA上。相比之下，人类HEPA相关蛋白(HARP)和退火解旋酶2是SNF2解旋酶样蛋白家族中遥远的成员，它们的作用方式与解旋酶相反，并将DNA卷回双链形式。HARP基因突变导致一种罕见的常染色体、隐性和多效性疾病，称为Schimke免疫性骨质疏松症(SIOD)，这一发现突显了HARP的生物学重要性。HARP和AH2都与参与DNA复制和修复的蛋白质相互作用。缺乏HARP和AH2的细胞对DNA损伤剂更敏感，这表明它们是有效的DNA修复所必需的。我们的长期目标是确定特定的DNA修复 需要HARP和AH2的通路，并确定它们是否可以被操纵用于癌症治疗。本研究的目的是：(1)研究HARP和AH2在其天然复合体中的生化和细胞功能；(2)发展研究退火解旋酶的新方法和途径；(3)发现新的退火解旋酶。这项工作应该提供坚实的知识基础，我们预计这将导致这些新酶未来的生物医学应用。因此，我们的研究具有非常重要的意义，因为它将有助于阐明DNA结构与基因组稳定性、DNA修复和SIOD之间的新机制。

 DESCRIPTION (provided by applicant): The structure and integrity of our genetic material is of great biological significance. DNA is a dynamic molecule and it is essential to identify and to characterize the enzymes that alter DNA structure. DNA helicases are ATP-driven motor proteins that unwind DNA, and help load single-stranded DNA binding proteins, such as RPA, onto the DNA. In contrast, the human HepA-related protein (HARP) and Annealing Helicase 2, distant members of the SNF2 family of helicase-like proteins, act in an opposite manner to helicases and rewind DNA back into its double-stranded form. The biological importance of HARP has been underscored by the discovery that mutations in the harp gene cause a rare autosomal, recessive, and pleiotropic disorder known as Schimke immuno-osseous dysplasia (SIOD). Both HARP and AH2 interact with proteins involved in DNA replication and repair. Cells lacking HARP and AH2 are more sensitive to DNA damaging agents, suggesting they are required for efficient DNA repair. Our long term objectives are to identify the specific DNA repair pathways that require HARP and AH2, and to determine if they can be manipulated for cancer therapy. The aims of the proposed study are: (1) to investigate the biochemical and cellular functions of HARP and AH2 in their native complexes, (2) to develop new methods and approaches for the study of annealing helicases, and (3) to discover new annealing helicases. This work should provide a strong foundation of knowledge, which we anticipate will lead to future biomedical applications of these new enzymes. Thus, our proposed study is highly significant because it will help elucidate novel mechanisms linking DNA structure with genome stability, DNA repair, and SIOD.