X-RAY ANALYSIS OF REPLICATION AND REPAIR PROTEINS

该子项目是利用 由NIH/NCRR资助的中心赠款提供的资源。子项目和 研究者（PI）可能从另一个NIH来源获得主要资金， 因此可以在其他CRISP条目中表示。所列机构为 中心，不一定是研究者的机构。 这项工作的目标是基于结构的理解1）复制起始和2）核苷酸切除修复（NER）。复制在基因组上的多个位点启动，称为DNA复制起点。专门的蛋白质复合物在这些位点结合，并准备复制的双链体。这些集合体的活性受到严格控制，以确保每个细胞周期只产生一个基因组拷贝。这些大型复合物的结构、调节和作用机制尚不完全清楚。我们的工作具有实际意义，因为起源复合物的调节变化有助于人类癌症。对细菌复合物的研究将为开发新型抗生素提供急需的靶点。 NER中的第一步由三种蛋白质执行：UvrA，UvrB和UvrC。UvrA+UvrB集合监测DNA并识别损伤。在遇到损伤时，UvrA退出复合物，留下UvrB稳定地结合在损伤部位处或附近。损伤搜索、DNA复合物的形成和UvrA的解离受ATP调节。然后UvrB招募内切核酸酶UvrC，催化病变两侧的切口。 额外的加工反应导致原始DNA序列的恢复。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. The goal of this work is a structure-based understanding of 1) replication initiation and 2) nucleotide excision repair (NER). Replication initiates at multiple sites on the genome called origins of DNA replication. Specialized protein complexes bind at these sites and prepare the duplex for replication. The activity of these ensembles is tightly controlled to ensure that only one copy of the genome is made per cell cycle. The architecture, regulation and mechanisms of action of these large complexes are incompletely understood. Our work is of practical significance because regulatory changes in origin complexes contribute to human cancers. Efforts with bacterial complexes will provide much needed targets for development of novel antibiotics. The first steps in NER are performed by three proteins: UvrA, UvrB and UvrC. The UvrA+UvrB ensemble monitors DNA and recognizes damage. On encountering damage, UvrA exits the complex, leaving UvrB stably bound at or near the lesion site. Damage searching, formation of the DNA complex and dissociation of UvrA are regulated by ATP. UvrB then recruits the endonuclease UvrC, which catalyzes incisions on either side of the lesion. Additional processing reactions lead to restoration of the original DNA sequence.