Determining the Essential Role of the Major Phosphoprotein of Vaccinia Virus: Vp11

病毒DNA复制和形态发生所必需的许多病毒蛋白的活性受磷酸化调控。痘苗病毒（VV）就是这种情况，它是痘病毒科中最了解的成员，这一点越来越清楚。痘病毒编码其自身转录和复制病毒基因组所需的绝大多数酶成分。这种来自宿主的显著自主性使VV成为最重要的真核生物化学和遗传模型系统之一。VV的研究继续揭示平行系统，如DNA复制，染色质凝聚，蛋白质的翻译后修饰，以及激酶和磷酸酶的动态方面。特别是，VV编码两种蛋白激酶（F10和B1）和一种双特异性磷酸酶（H1）。这些酶在病毒的生命周期中都是必不可少的。然而，动态磷酸化在病毒生命周期中发挥的确切分子作用在很大程度上仍不清楚。这项研究的核心是牛痘病毒蛋白Vp11，它是一种11- kda -磷酸丝氨酸蛋白。虽然Vp11（由F17基因编码）是病毒粒子中最丰富的蛋白质（就分子数量而言），但其在体内的确切功能仍然难以捉摸。因此，本研究的主要目标是确定Vp11在体内的功能。Vp11在体外与DNA结合，长期以来一直被认为参与病毒基因组DNA的凝聚。通过调节核酸结合活性，蛋白磷酸化可以是基因表达的正或负调节因子。磷酸化对于蛋白质的寡聚化也是必要的。此外，蛋白质磷酸化也可能是蛋白质适当的亚细胞定位所必需的，或者可能对蛋白质在体内的稳定性至关重要。本项目旨在探索这些场景。该项目的最新研究结果表明，MAP/ERK激酶信号通路在VV生命周期中发挥着重要作用。牛痘作为一种模型系统的可追溯性，允许对宿主细胞的这种可能贡献进行解剖。这些过程的各个方面在本项目中通过Vp11的集中分子表征以及MAP/ERK信号通路在痘病毒生命周期中的作用来解决。这个项目中描述的研究涉及一种叫做牛痘的动物病毒。牛痘是用来根除天花的活疫苗。生物化学家对牛痘病毒的研究长期以来为人类细胞更复杂的运作提供了见解。人类细胞的正常生长需要多种形式的控制（也称为“调节”）。没有这种调节，细胞生长就会变得异常。最常见的调节类型是一种简单的化学过程，通过将磷酸盐离子放置在某些类型的蛋白质上。这种调节被称为“磷酸化”。这项由美国国家科学基金会资助的研究将通过使用更简单，因此更易于处理的病毒模型系统，为这一关键事件提供一个窗口。

The activities of many viral proteins required for viral DNA replication and morphogenesis are regulated by phosphorylation. That this is the case in vaccinia virus (VV), which is the best-understood member of the Poxviridae, is increasingly clear. Poxviruses encode the vast majority of their own enzymatic components required for the transcription and replication of their viral genome. This remarkable autonomy from the host makes VV one of the most premier eukaryotic biochemical and genetic model systems available. The study of VV continues to shed light on parallel systems such as DNA replication, chromatin condensation, post-translational modification of proteins, and dynamic aspects of kinases and phosphatases. In particular, VV encodes two protein kinases (F10 and B1) and a dual-specificity phosphatase (H1). These enzymes are all essential in the viral life cycle. However, the precise molecular role dynamic phosphorylation plays during the viral life cycle remains largely undefined. The vaccinia viral protein that is at the heart of this research, Vp11, is an 11-kDa-phosphoserine protein. Although Vp11 (encoded by the gene F17) is the most abundant protein (in terms of number of molecules) in the virion, its precise in vivo function(s) remains elusive. As such, the primary goal of this research is to determine the in vivo function(s) of Vp11. Vp11 binds to DNA in vitro, and has long been postulated to be involved in condensation of the viral genomic DNA. By modulating nucleic acid-binding activity, protein phosphorylation can be a positive or negative regulator of gene expression. Phosphorylation may also be necessary for the oligomerization of a protein. Furthermore, protein phosphorylation can also be required for the proper subcellular localization of a protein, or may be critical for the protein's stability in vivo. This project is designed to explore these scenarios. Recent results from this project point to an important role of the MAP/ERK kinase-signaling pathway during the VV life cycle. The proven tractability of vaccinia as a model system allows a dissection of this possible contribution of the host cell. Aspects of these processes are addressed within this project by a focused molecular characterization of Vp11 as well as the role of the MAP/ERK signaling pathway in the life cycle of poxviruses.The research described in this project involves an animal virus called vaccinia. Vaccinia was the live vaccine used to eradicate smallpox. The study of vaccinia virus by biochemists has long provided insights into the more complicated workings of human cells. For the correct growth of a human cell, many forms of control (also called "regulation") are required. Without this regulation, cell growth becomes abnormal. The most common type of regulation is a simple chemical process by which a phosphate ion is placed on certain types of protein. Regulation of this sort is termed "phosphorylation". This NSF-funded research will provide a window into this crucial event by using a much simpler, and therefore more tractable, viral model system.