GENETICS OF MYXOPHAGES

噬菌体遗传学

• 批准号: 6180997
• 负责人: PHILIP A YOUDERIAN
• 金额: $ 5.92万
• 依托单位: TEXAS A&M UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 1995
• 资助国家: 美国
• 起止时间: 1995-02-01 至 2004-01-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6180997
• 关键词: Myxococcus; bacterial virus; gene mutation; genetic promoter element; lysogeny; microorganism culture; molecular cloning; nucleic acid sequence; site directed mutagenesis; virus genetics

The sequence of the G+C-rich temperate bacteriophage Mx8 genome shows that it is unlike any phage examined in detail to date. Our continuing studies of Mx8 genes and their functions will likely reveal new regulatory paradigms that are also used by its M. xanthus host during the process of multicellular development. We will try to uncover the secret of a unique phage-host adaptation: how is the Mx8 prophage maintained stably throughout M. xanthus multicellular development, despite the dramatic, successive, global changes in gene regulation that occur during this cycle? We will complete the sequence of the remaining third of the 50 kb Mx8 genome, to identify the Mx8 genes involved in lysogenic development, lytic development, and the stability of the Mx8 prophage throughout the multicellular developmental cycle of its host. The structure and function of a divergent pair of Mx8 promoters will be dissected, to learn what sequence elements are critical for strong promoter function in M. xanthus. A single-copy plasmid will be used to trap vegetative M. xanthus promoters, to expose their consensus sequence elements. Phage promoters will be cloned, to learn when they are activated during the lytic cycle of phage growth, or from an Mx8 prophage during the multicellular development of an M. xanthus lysogen. Mutations will be made in the genes controlling Mx8 superinfection immunity, to understand its novel dosage-dependent mechanism, in the repressor gene, to permit the inducible expression of genes from a strong Mx8 promoter and in the phage terminase, to construct high-frequency generalized transducing mutants. Temperature-sensitive mutations in Mx8 will be isolated to characterize its essential functions, and we will attempt to use conditionally-polar insertions in new ways to identify both nonessential phage functions, and to correlate phage genes with their protein products.

富含G+C的温带噬菌体MX8基因组的序列表明，它与迄今为止详细检查的任何噬菌体不同。我们对MX8基因及其功能的持续研究可能会揭示其在多细胞发育过程中Xanthus宿主也使用的新调节范例。我们将尝试揭示独特的噬菌体宿主适应的秘密：尽管在此周期中发生的基因调节中发生了巨大，连续的，全球的变化，但在整个Xanthus多细胞发育中，MX8预言如何稳定地保持稳定？我们将完成50 kb Mx8基因组中其余的三分之一的序列，以确定在其宿主的多细胞发育周期中涉及溶晶发育，裂解发育以及MX8预言的稳定性的MX8基因。 将解剖一对MX8启动子的结构和功能，以了解哪些序列元素对于Xanthus M. Xanthus中强启动子功能至关重要。 单拷贝质粒将用于捕获营养的Xanthus M. Xanthus启动子，以暴露其共识序列元素。 噬菌体启动子将被克隆，以学习何时在噬菌体生长的裂解循环中激活它们，或者在Xanthus裂解菌的多细胞发育过程中从MX8预言中学习。将在控制MX8超染射免疫的基因中进行突变，以了解其新型剂量依赖性机制，即阻遏物基因，以允许从强的MX8启动子和噬菌体终端酶中诱导基因的诱导表达，以构建高频率的通用传播突变体。 MX8中的温度敏感突变将被隔离以表征其必不可少的功能，我们将尝试以新的方式使用有条件的极线插入来识别两个非必需的噬菌体功能，并将噬菌体基因与其蛋白质产物相关联。