Assembly of the poxvirus transcription machinery and its activation upon infection

痘病毒转录机器的组装及其感染后的激活

• 批准号: 497462554
• 负责人: Professor Dr. Utz Fischer
• 金额: --
• 依托单位: Lehrstuhl für Biochemie I
• 依托单位国家: 德国
• 项目类别: Research Grants
• 资助国家: 德国
• 项目状态: 未结题
• 来源: https://gepris.dfg.de/gepris/projekt/497462554?language=en
• 关键词: Assembly; poxvirus; transcription; machinery; its

Poxviruses express and replicate their genomes exclusively in the cytoplasm of their hosts. Consequently, the virus has only limited access to cellular enzymes ensuring transcription, RNA maturation and replication, as these are sequestered in the nucleus. Poxvirus propagation therefore critically depends on a virus-encoded gene expression machinery consisting of a multi-subunitRNA polymerase (vRNAP), transcription and mRNA processing/maturation factors. This virus-factor driven propagation strategy further entails that virions must contain all components for early transcription in a “ready-to-go” fashion, allowing gene expression to start immediately upon cell entry. How the relevant factors are assembled, packaged into viral progenies and activated upon infection is largely unknow. In previous studies we have established a purification strategy for vRNAP complexes from Vaccinia, a prototypic nonpathogenicpoxvirus. We discovered a stable supramolecular complex (termed “complete vRNAP”) that unites the core polymerase with the early transcription factors Rap94 and VETF-s/l, the capping enzyme D1/12 and the termination factor NPH-I. This unit is sufficient for the execution of the entire early transcription cycle, including early promotor recognition, initiation, elongation, mRNA capping and termination in vitro. In the present grant proposal, we will investigate how and at what stage in the viral infection cycle the complete vRNAP is assembled and whether it constitutes the “ready-to-go” unit incorporated into newly formed virions. As part of these studies, we will also ask how these processes are influenced by viral and host factors. We expect insight into key aspects of poxvirus propagation and its interplay with the host during infection.

痘病毒仅在宿主的细胞质中表达和复制其基因组。因此，病毒只能有限地接触确保转录、RNA 成熟和复制的细胞酶，因为这些酶被隔离在细胞核中。因此，痘病毒的传播关键取决于病毒编码的基因表达机制，该机制由多亚基RNA聚合酶（vRNAP）、转录和mRNA加工/成熟因子组成。这种病毒因子驱动的繁殖策略进一步要求病毒粒子必须以“准备就绪”的方式包含早期转录的所有组件，从而允许基因表达在进入细胞后立即开始。相关因子是如何组装、包装成病毒后代并在感染时激活的，目前尚不清楚。在之前的研究中，我们已经建立了一种从痘苗病毒（一种原型非致病性痘病毒）中纯化 vRNAP 复合物的策略。我们发现了一种稳定的超分子复合物（称为“完整 vRNAP”），它将核心聚合酶与早期转录因子 Rap94 和 VETF-s/l、加帽酶 D1/12 和终止因子 NPH-I 结合在一起。该单元足以执行整个早期转录周期，包括早期启动子识别、起始、延伸、mRNA加帽和体外终止。在目前的资助提案中，我们将研究完整的 vRNAP 在病毒感染周期中如何以及在哪个阶段组装，以及它是否构成并入新形成的病毒体中的“准备就绪”单元。作为这些研究的一部分，我们还将询问这些过程如何受到病毒和宿主因素的影响。我们期望深入了解痘病毒传播的关键方面及其在感染过程中与宿主的相互作用。