DNA PRECURSOR DYNAMICS IN ANIMAL CELLS

DNA前体生物合成的酶是 抗癌，抗病毒和抗微生物药物，因为代谢 脱氧核糖核苷三磷酸（dNTPs）的作用仅限于其 作为DNA前体，抑制特定的 脱氧核糖核苷酸提供了一种选择性的方式来阻止DNA复制， 肿瘤细胞或感染细胞。 核酸的有效利用 化疗中的抗代谢药物需要了解 影响酶的细胞内组织和调节机制 dNTP生物合成。 这样的理解也可能导致洞察到 DNA合成的控制--包括复制和修复。 该方案的具体目标包括：（1）确定机制 控制DNA前体库的细胞内分布;（2） 定义有效DNA前体浓度之间的关系， DNA复制的速率和准确性;（3）确定细胞内 dNTP生物合成酶之间的关联;（4）评估 假设脱氧核糖核苷酸库是 烷化剂的致突变作用。 该项目使用培养的哺乳动物细胞和疫苗病毒作为生物 用于分析dNTP生物合成之间的细胞内关联的系统 酶和DNA前体库的细胞内分布。 次 项目集中在（1）病毒编码形式的结构和调节 核糖核苷酸还原酶，（2）脱氧核糖核苷酸池作为目标， 自发和化学诱导诱变，（3）细胞分析 在dNTP代谢中具有特异性改变的突变体，（4）测定 核内和核内核苷酸库螯合的基础 线粒体，和（5）分析超分子组件， 核糖核苷酸还原酶和dNTP生物合成的其它酶。

Enzymes of DNA precursor biosynthesis are targets for the actions of anticancer, antiviral, and antimicrobial drugs, because the metabolic roles of deoxyribonucleoside triphosphates dNTPs) are limited to their functions as DNA precursors, inhibition of the synthesis of a particular deoxyribonucleotide presents a selective way to block DNA replication in a neoplastic cell or an infected cell. Effective use of nucleic acid antimetabolites in chemotherapy requires understanding of the intracellular organization and regulatory mechanisms affecting the enzymes of dNTP biosynthesis. Such understanding may lead also to insight into the control of DNA synthesis--both replication and repair. Specific aims of this program include: (1) to define mechanisms controlling the intracellular distribution of DNA precursor pools; (2) to define relationships between effective DNA precursor concentrations and the rate and accuracy of DNA replication; (3) to define intracellular associations among enzymes of dNTP biosynthesis; and (4) to evaluate the hypothesis that deoxyribonucleotide pools are significant targets for the mutagenic effects of alkylating agents. This project uses cultured mammalian cells and vaccine virus as biological systems for analyzing intracellular associations among dNTP biosynthetic enzymes and the intracellular distribution of DNA precursor pools. Sub- projects focus upon (1) the structure and regulation of a virus-coded form of ribonucleotide reductase, (2) deoxyribonucleotide pools as targets for spontaneous and chemically induced mutagenesis, (3) analysis of cell mutants with specific alterations in dNTP metabolism, (4) determination of the basis for sequestration of nucleotide pools in nuclei and in mitochondria, and (5) analysis of supramolecular assemblies involving ribonucleotide reductase and other enzymes of dNTP biosynthesis.