VIRUS CHROMOSOME STRUCTURE: ROLE IN DEVELOPMENT

我们正在研究病毒的形态发生，使用噬菌体伽马作为模型 系统我们的工作集中在几个病毒组装步骤，处理 尤其是DNA包装。病毒组装的第一个方面， 研究的是基因组识别。所有的病毒都面临着 从核酸中分离出病毒染色体。总 解决这个问题的办法是病毒产生一种识别蛋白 特异性结合病毒基因组。对于伽马，识别是 通过末端酶的作用完成，病毒DNA包装 酵素终止酶特异性结合γ DNA上的位点（cosB）， 前头部，DNA包装在其中的空蛋白质外壳。我们 感兴趣的是终止酶与DNA和DNA的相互作用， 船首。第二个方面是DNA加工。许多病毒产生 后代DNA是线性聚合物的形式， 在包装过程中。对于伽马来说，DNA处理也是功能之一 的末端酶，其在cosN处引入交错切口，以产生 病毒体DNA分子上的粘性末端。第三个方面是 组装过程中有序蛋白质-蛋白质相互作用的分子基础。 病毒的结构，如衣壳，是在一个有序的系列产生的 的反应。在许多情况下，例如对于噬菌体T4尾， 会议的顺序安排得很好。一般的解释是 控制反应的顺序是当一个亚基 添加到生长的结构中，形成反应性位点用于结合 下一个组件，这反过来又为下一个组件生成一个结合位点。 亚单位关于这些亚基-亚基相互作用， 分子水平。终止酶与前体结合， 这样做，我们已经开始了这样的研究。第四，对于具有 溶原性（或潜伏性）周期。我们遇到过这样的情况， 末端酶表达的调节明显被破坏， 导致潜在溶原的丧失。看起来很紧 除了抑制外，还控制末端酶的表达， 我们现正研究这些建议。弗斯，把伽马DNA注射到宿主体内 细胞还不太了解。有证据表明，特定的DNA： 蛋白质相互作用对于注射很重要，因为注射是 对于DNA分子来说非常差， 正常的右染色体末端。我们分离出了一个点突变 因此可以开始详细的研究。

We are studying virus morphogenesis, using bacteriophage gamma as a model system. Our work focusses on several virus assembly steps, dealing especially with DNA packaging. The first aspect of virus assembly we are studying is genome recognition. All viruses face the problem of encapsidating the virus chromosome from a nucleic acids. The general solution to the problem is that the virus produces a recognition protein that specifically binds to the viral genome. For gamma, recognition is accomplished through the action of terminase, the viral DNA packaging enzyme. Terminase specifically binds to a site (cosB) on gamma DNA and to the prohead, the empty protein shell into which DNA is packaged. We are interested in the interaction of terminase with both he DNA and the prohead. The second aspect is DNA processing. Many viruses produce progeny DNA is the form of linear polymers that are cut to unit length during packaging. For gamma,DNA processing is also one of the functions of terminase, which introduces staggered nicks, at cosN, to generate the cohesive ends found on virion DNA molecules. The third aspect is the molecular basis for ordered protein-protein interactions during assembly. Viral structures, such as the capsid, are produced in an ordered series of reactions. In a number of cases, such as for the phage T4 tail, the order of assembly is well worked out. The general explanation for how sequential ordering of reactions is controlled is that when a subunit adds to a growing structure, a reactive site is formed for binding the next component, which in turn generates a binding site for the next subunit. Little is known about these subunit-subunit interactions at the molecular level. Terminase binds the prohead, and apparently is activated to do so and we have begun such a study. Fourth, for viruses that have a lysogenic (or latent) cycle. We have encountered situations in which regulation of the expression of terminase is apparently disrupted, leading to the loss of potential lysogens. It appears that are tight controls on the expression of terminase quite apart from repression, and these are being examined. Firth, injection of gamma DNA into the host cell is not well understood. There exists evidence that specific DNA: protein interactions are important for injection, because injection is very poor for DNA molecules that have a substitution that replaces the normal right chromosomal end. We have isolated a point mutation affecting injection and can therefore begin detailed studies.