VIRUS CHROMOSOME STRUCTURE--ROLE IN DEVELOPMENT

建议用实验来研究病毒dna的作用机制。 包装，使用噬菌体Lambda作为模型系统。兰布达，就像 噬菌体T3和T7以及疱疹病毒通过以下方式产生病毒染色体 在多聚体前体DNA中引入特定的切割。对于其中的每一个 病毒，一组复杂的DNA位点指示包装机械 切割并打包病毒DNA。Lambda DNA包装系统是最好的 了解这群人。为了启动DNA包装终止酶，lambda DNA包装酶，结合到COSB位点，并引入交错 邻近部位的NICKS，CoSN，以产生病毒粒子的粘连末端 DNA然后，终端酶结合一个空的蛋白质壳，前头，和 随后DNA移位到头部，伴随着三磷酸腺苷 水解液。包装终止发生在运输过程中 包装机械遇到下一个CoSN，该CoSN被擦除以生成 病毒DNA的末端。终止需要CoSN、COSB和 新发现的站点，CosQ。 拟议中的实验将详细检查 在启动和终止过程中与cos位点的终止酶 包装。这些相互作用将在分子水平上定义， 给出了关于终止酶识别DNA的信息，以及关于 参与DNA识别的终止酶结构域。一系列 包装过程中的中间体，包括终止酶-DNA复合体， 暂停的移位复合体和暂停的终止复合体将 详细检查以确定蛋白质的组成和结构 这些复合体。这些信息应该有助于理解 包装过程中包装机械内部的结构变化 进程。一个关于CosQ如何参与改变移位的模型 将复合体转化为终端复合体将进行测试。ATP具有多个角色 在DNA包装中作为效应器分子和能源。的研究 两个ATPase活性改变的突变终止符将定义 三磷酸腺苷在缺口、粘性末端分离和转位中的作用 终止酶活性。DNA包装，和其他DNA-蛋白质一样 事务，如转录、重组和复制， 涉及蛋白质组装和DNA之间的复杂相互作用。 在分子水平上理解这些过程是一个主要目标 生物学。

Experiments are proposed to investigate the mechanism of virus DNA packaging, using bacteriophage lambda as a model system. lambda, like phages T3 and T7 and the herpesviruses, generates virion chromosomes by introducing specific cuts in multimeric precursor DNA. For each of these viruses, a complex array of DNA sites instructs the packaging machinery to cut and package the viral DNA. The lambda DNA packaging system is the best understood of the group. To initiate DNA packaging terminase, the lambda DNA packaging enzyme, binds to the cosB site, and introduces staggered nicks in the adjacent site, cosN, to generate the cohesive ends of virion DNA. Terminase then binds an empty protein shell, the prohead, and translocation of the DNA into the head ensues, accompanied by ATP hydrolysis. Termination of packaging occurs when the translocating packaging machinery encounters the next cosN, which is nicked to generate the terminus of the virion DNA. Termination requires cosN, cosB and the newly discovered site, cosQ. The proposed experiments will examine in detail the interactions of terminase with the cos sites during initiation and termination of packaging. These interactions will be defined at the molecular level, giving information about DNA recognition by terminase, and about the domains of terminase involved in DNA recognition. A series of intermediates in the packaging process, including a terminase-DNA complex, a paused translocating complex, and a paused termination complex will be examined in detail to determine the protein composition and structures of the complexes. This information should lead to an understanding of structural changes within the packaging machinery during the packaging process. A model for how cosQ participates in changing the translocating complex into a termination complex will be tested. ATP has multiple roles in DNA packaging as an effector molecule and an energy source. Studies of mutant terminases altered for the two ATPase activities will define the role of ATP in the nicking, cohesive end separation, and translocation activities of terminase. DNA packaging, like other DNA-protein transactions such as transcription, recombination and replication, involves complex interactions between a protein assembly and the DNA. Understanding these processes at the molecular level is a major goal of biology.