MOLECULAR STUDIES OF PROTEIN-DNA INTERACTIONS

我们试图在分子水平上理解 生物体保持其完整性的各种方式 基因组，同时适应多样性的需要。我们的研究 目前的努力集中在两个相关的过程，同源 重组和DNA错配修复。我们有兴趣 研究了靶向关键DNA中间体的蛋白质， 同源重组称为霍利迪连接。这 连接标志着两个同源DNA的交换点 正在经历重组使用人工构建的 霍利迪路口，我们已经确定，一个组蛋白八聚体是一个 对交界处的迁移形成障碍。然而，马达蛋白， E.大肠杆菌RuvAB和假定的真核对应物可以 促进连接通过核小体的运动。 错配修复以E.大肠杆菌甲基导向 错配修复途径，在维持 基因组的完整性。错配可以通过DNA产生 复制错误，同源重组和自发 DNA损伤。细菌错配修复系统的组成 在大肠杆菌中由mutS和mutL基因编码。大肠杆菌， 在原核生物和真核生物中都是保守的，但在人类中有缺陷。 编码错配修复酶的基因与 遗传性结肠癌我们有兴趣了解 错配识别的分子机制 MutS蛋白。通过光交联和定点 诱变，我们已经确定了一个关键的苯丙氨酸残基 参与Taq和E.杆菌 MutS蛋白。

We seek to understand at a molecular level the various ways by which an organism maintains the integrity of its genome while accommodating the need for diversity. Our research efforts currently focus on two related processes, homologous recombination and DNA mismatch repair. We are interested in studies of proteins that target a key DNA intermediate in homologous recombination known as the Holliday junction. This junction marks the point of exchange of two homologous DNAs that are undergoing recombination. Using artificially constructed Holliday junctions, we have determined that a histone octamer is a barrier to migration of the junction. However, motor proteins like E. coli RuvAB and presumptive eukaryotic counterparts can promote movement of the junction through a nucleosome. Mismatch repair, exemplified by the E. coli methyl-directed mismatch repair pathway, plays critical roles in maintaining the integrity of a genome. Mismatches can arise through DNA replication errors, homologous recombination and spontaneous DNA damage. Components of the bacterial mismatch repair system encoded by the mutS and mutL genes in E. coli, are highly conserved in both prokayotes and eukaryotes with defects in human genes encoding mismatch repair enzymes being implicated in hereditary colon cancer. We are interested in understanding the molecular mechanism involved in mismatch recognition by the MutS protein. Through photocross-linking and site-directed mutagenesis, we have identified a critical phenylalanine residue involved in heteroduplex DNA binding in both Taq and E. coli MutS proteins.