Research Paper "Structure and Mechanism of Human DNA Polymerase " Published in Nature

July 1, 2010

On June 24, graduate student Zhao Ye's research paper "Structure and Mechanism of Human DNA Polymerase was published in Nature (DOI: 10.1038/nature09196). Zhao Ye is the second author. Zhao is a graduate student in a joint training program by Institute of Neclear-Agricultural Science, College of Agriculture and Biotechnology, Zhejiang University, and Laboratory of Molecular Biology, NIDDK, NIH, USA.

As is universally known, UV radiation can cause human DNA damage and the termination of DNA replication. The production of CPD, in particular, will cause the failure in repair by most of the repair systems. In this regard, a human DNA polymerase, namely DNA Polymerase , can be highly efficient and accurate in translesion synthesis. Defects in Polymerase will result in a kind of skin disease called XPV, the patients of which are extremely sensitive to ultraviolet and suffer high probability of skin cancer. With the research methodology of structural biology, the paper systematically looks into the process of translesion CPD synthesis enabled by Polymerase , and the features of Polymerase which can fully explain the mechanism of the polymerase. In addition, because the polymerase is not only related to Somatic hypermutation, but also the antagonist of anti-cancer drug Cisplatin, the future work will be of great pharmaceutical and clinical significance. This project is a joint project sponsored by Institute of Neclear-Agricultural Science, Laboratory of Molecular Biology NIH and Osaka University. It s also funded by China Scholarship Council. Zhao Ye s advisor is Professor Hua Yuejin.

Abstract: The variant form of the human syndrome xeroderma pigmentosum (XPV) is caused by a deficiency in DNA polymerase (Pol ), a DNA polymerase that enables replication through ultraviolet-induced pyrimidine dimers. Here we report high-resolution crystal structures of human Pol at four consecutive steps during DNA synthesis through cis-syn cyclobutane thymine dimers. Pol acts like a molecular splint to stabilize damaged DNA in a normal B-form conformation. An enlarged active site accommodates the thymine dimer with excellent stereochemistry for two-metal ion catalysis. Two residues conserved among Pol orthologues form specific hydrogen bonds with the lesion and the incoming nucleotide to assist translesion synthesis. On the basis of the structures, eight Pol missense mutations causing XPV can be rationalized as undermining the molecular splint or perturbing the active-site alignment. The structures also provide an insight into the role of Pol in replicating through D loop and DNA fragile sites.