Biochemical Properties of gpNu1, a Phage Lambda Protein Required for Viral Assembly

Catalano 9728550 1.技术包装空壳内的脱氧核糖核酸通过核蛋白中间产物的有序递增进行，需要终止酶，这是所有双链脱氧核糖核酸噬菌体共有的一种酶。酶的亚基gpNu1和GPA组装在一个多元素的DNA结合位点上，产生核蛋白复合体，从连接体中切除单个基因组并将其插入衣壳中。本研究在分子水平上研究了λ噬菌体1 gpNu1蛋白的生化和生物物理性质，这些性质是导致所涉及的核蛋白中间体的协同组装和异常稳定性的原因。目的是了解gpNu1自结合相互作用和gpNu1 GPA蛋白相互作用在组装和稳定核蛋白复合体中的作用。这些实验旨在详细了解gpNu1自结合和与DNA的协同结合之间的热力学联系，以及随后GPA和催化活性基因组包装复合体的组装。本研究还试图确定gpNu1多肽中负责观察到的gpNu1寡聚、gpNu1 GPA相互作用和与DNA协同结合的功能结构域。由于终止酶在许多双链DNA病毒中是常见的，本研究的结果可能普遍适用于理解其他病毒的组装和堆积机制。2.非技术性多种生物过程需要将多种蛋白质组装到细胞和/或病毒的染色体内的特定位置。这些复合体中的许多最初作为稳定的中间体组装，然后转化为高度流动的生物机器。精致的核蛋白(DNA和蛋白质)复合体负责关键的生物学过程，包括染色体的复制、信使RNA的合成和传染性病毒的组装。这项研究旨在阐明病毒在细胞内组装的过程和病毒染色体包装的复杂过程，特别是涉及终止酶的参与，该多蛋白质机器将病毒染色体插入噬菌体Lambda的保护性蛋白外壳中，Lambda是一种感染细菌的病毒。这种酶在许多双链DNA病毒中是常见的，是一系列有序的核蛋白复合体的组成部分，而核蛋白复合体对病毒组装至关重要。实验检测了gpNu1的生化和生物物理性质，gpNu1是一种L包装蛋白，负责病毒染色体包装中核蛋白中间体的组装和异常稳定性。重要的是，来自这些研究的数据将进一步深入了解驱动稳定的核蛋白复合体组装的基本原理，这些复合体涉及对病毒和细胞复制都至关重要的各种生物学过程。

Catalano 9728550 1. Technical Packaging of DNA within an empty pre-formed capsid proceeds through an ordered progression of nucleoprotein intermediates requires terminase, an enzyme common to all of the double-stranded DNA bacteriophages. The enzyme subunits, gpNu1 and gpA, assemble onto a multi-element DNA binding site generating a nucleoprotein complex, excising a single genome from the concatamer and inserting it into the capsid. This study examines, at the molecular level, the biochemical and biophysical properties of the lambda phage 1 gpNu1 protein which are responsible for the cooperative assembly and unusual stability of the nucleoprotein intermediates involved. The aims are to understand the roles of gpNu1 self-association interactions and gpNu1 gpA protein protein interactions in the assembly and stability of the nucleoprotein complexes critical to the assembly. The experiments are designed to provide a detailed understanding of the thermodynamic linkages between gpNu1 self-association and cooperative binding to DNA, and to the subsequent assembly of gpA and a catalytically competent genome packaging complex. This study also seeks to define functional domains within the gpNu1 polypeptide which are responsible for the observed oligomerization of gpNu1, for gpNu1 gpA interactions, and for cooperative binding to DNA. Since the terminase enzyme is common to many double-stranded DNA viruses, findings from this study may be generally applicable to the understanding of other viral assembly and packing mechanisms. 2. Non-Technical A variety of biological processes require the assembly of multiple proteins onto specific sites within the chromosomes of cells and/or viruses. Many of these complexes initially assemble as stable intermediates which are subsequently transformed into highly mobile biological machines. Elaborate nucleoprotein (DNA and protein) complexes are responsible for critical biological processes including the replication of chromosomes, the synthesis of messenger RNA, and the assembly of infectious viruses. This study is to elucidate the process of viral assembly within the cell and the complex process of viral chromosome packaging, specifically in the involvement of the terminase enzyme, the multi-protein machines which insert the viral chromosome within a protective protein shell in bacteriophage lambda, a virus which infects the bacteria E. coli. This enzyme, which is common to many double-stranded DNA viruses, is an integral part of an ordered series of nucleoprotein complexes which are critical to viral assembly. Experiments are carried out to examine the biochemical and biophysical properties of gpNu1, a phage l packaging protein, which are responsible for the assembly and unusual stability of the nucleoprotein intermediates involved in viral chromosome packaging. Importantly, the data derived from these studies will additionally yield insight into the basic principles driving the assembly of stable nucleoprotein complexes involved in a variety of biological processes critical to both viral and cellular replication.