Molecular Evolution and Life Cycle of Wolbachia Bacteriophage

沃尔巴克氏菌噬菌体的分子进化和生命周期

• 批准号: 7848059
• 负责人: SETH R BORDENSTEIN
• 金额: $ 24.31万
• 依托单位: VANDERBILT UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2008
• 资助国家: 美国
• 起止时间: 2008-09-01 至 2013-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7848059
• 关键词: Affect; Alphaproteobacteria; Animals; Applied Research; Arthropods; Bacteria; Bacteriophages; Biocontrols; Biology; Cell Culture Techniques; Cell Line; Cells; Coupled; Cytolysis; DNA; Development; Disease; Disease Vectors; Elements; Ensure; Environment; Equilibrium; Evolution; Female; Gene Deletion; Gene Pool; Genes; Genetic; Genetic Recombination; Genetic Variation; Genome; Genomics; Goals; Health; Horizontal Disease Transmission; Horizontal Gene Transfer; Human; Human Pathology; In Vitro; Infection; Insecta; Investigation; Knowledge; Laboratories; Lateral; Life; Life Cycle Stages; Life Style; Lysogeny; Lytic; Molecular; Molecular Biology; Molecular Evolution; Mutation; Organism; Parasites; Phase; Planets; Population; Predatory Behavior; Public Health; Reproduction; Research; Role; Sequence Analysis; Shapes; Specific qualifier value; Stress; Stress Tests; Structure; System; Testing; Therapeutic; Time; Transgenic Organisms; Variant; Virion; Virulence; Wolbachia; base; comparative; density; ds-DNA; egg; experience; extracellular; fitness; functional genomics; gene function; genome sequencing; in vivo; insect disease; killings; obligate intracellular parasite; particle; reproductive; theories; tool; trait; transposon/insertion element; vector

DESCRIPTION (provided by applicant): Wolbachia pipientis is one of the most prevalent obligate, intracellular bacteria in multicellular animals. By causing a diverse array of reproductive alterations in arthropods that favor the fitness of infected females, this bacterium has spread worldwide through hundreds of thousands of species. One of the unique genomic features to Wolbachia is an overabundance of mobile DNA including a temperate double-stranded DNA bacteriophage, called WO-B that has no known function. Our long term goal is to elucidate the mechanisms, relevance, and applications of this bacteriophage to the biology of Wolbachia. The specific hypothesis is that the bacteriophage is a mobile genetic parasite of Wolbachia, capable of integrating into and killing Wolbachia to ensure its own replication as a selfish element. We base that hypothesis on four observations: First, WO-B is widespread and infects 89% of all strains in the two major Wolbachia lineages that infect arthropods. Second, sequence analyses specify WO-B recombination and horizontal transmission between Wolbachia that co-infect the same host. Third, the presence of WO-B does not correlate with the capacity to induce reproductive alterations. Fourth, observations of WO-B particles from purified insect homogenates and from within lysed Wolbachia cells demonstrate that WO-B is active and may kill Wolbachia. Based on these observations, the experimental focus of this proposal is on the molecular evolution and predation of Wolbachia phage WO-B. The specific aims are to: 1. Determine the molecular evolutionary forces shaping Wolbachia bacteriophage. By completing this aim, we will answer three related questions: (Aim 1A) How does an obligate intracellular niche affect phage genome evolution? We will determine how the distinctive ecological conditions of an obligate intracellular bacterium affect genetic diversity in WO-B and we will compare this to the rules of phage genome evolution in free-living bacteria. (Aim 1B) What classes of phage genes are under selection and do they correlate with gene functions such as integration, lysis, lysogeny, virulence, or structure? (Aim 1C) What are the number, diversity, and functions of phage genes that laterally transfer to and from Wolbachia co-infections? Our preliminary results suggest rampant horizontal phage transfer coupled with strong purifying selection. 2. Determine if bacteriophage kill Wolbachia and thereby regulate intrahost densities and Wolbachia's effects on hosts. Here, we will answer two questions related to phage function: (Aim 2A) In a controlled laboratory environment, do lytic phages prey on Wolbachia endosymbionts? (Aim 2B) Does environmental stress trigger phage lysis and does this variation in lysis correspond to variation in Wolbachia densities and interactions with the host? We propose these subaims as an alternative to the prevailing view that phage may be adaptive to Wolbachia's ability to modify arthropod reproduction. Our preliminary studies suggest their principal role is predation of Wolbachia.

描述（由申请人提供）：管状沃尔巴克氏体是多细胞动物中最普遍的专性细胞内细菌之一。通过在节肢动物中引起一系列有利于受感染雌性的生殖改变，这种细菌已经通过数十万种物种传播到世界各地。沃尔巴克氏体的一个独特的基因组特征是大量的可移动DNA，包括一种温带双链DNA噬菌体，称为WO-B，它没有已知的功能。我们的长期目标是阐明这种噬菌体在沃尔巴克氏体生物学中的机制、相关性和应用。具体假设是，噬菌体是沃尔巴克氏体的一种可移动的遗传寄生虫，能够融入并杀死沃尔巴克氏体，以确保自身作为自私元素的复制。我们的假设基于四个观察结果：首先，在感染节肢动物的两个主要沃尔巴克氏体谱系中，WO-B是广泛存在的，感染了89%的所有菌株。其次，序列分析明确了共同感染同一宿主的沃尔巴克氏体之间的WO-B重组和水平传播。第三，WO-B的存在与诱导生殖改变的能力无关。第四，从纯化的昆虫匀浆和裂解的沃尔巴克氏体细胞中观察到的WO-B颗粒表明，WO-B具有活性，可能杀死沃尔巴克氏体。基于这些观察结果，本课题的实验重点是沃尔巴克氏体噬菌体WO-B的分子进化和捕食。具体目标是：1。确定形成沃尔巴克氏体噬菌体的分子进化力量。通过完成这一目标，我们将回答三个相关问题：（目标1A）专性细胞内生态位如何影响噬菌体基因组进化？我们将确定专性胞内细菌的独特生态条件如何影响WO-B的遗传多样性，并将其与自由生活细菌中噬菌体基因组进化的规则进行比较。（Aim 1B）选择哪些种类的噬菌体基因？它们是否与基因功能相关，如整合、裂解、溶原、毒力或结构？（Aim 1C）在沃尔巴克氏体合并感染中横向转移的噬菌体基因的数量、多样性和功能是什么？我们的初步结果表明，猖獗的水平噬菌体转移加上强大的净化选择。2. 确定噬菌体是否杀死沃尔巴克氏体，从而调节宿主内密度和沃尔巴克氏体对宿主的影响。在这里，我们将回答与噬菌体功能相关的两个问题：（Aim 2A）在受控的实验室环境中，溶解噬菌体是否捕食沃尔巴克氏体内共生菌？（Aim 2B）环境压力是否会触发噬菌体裂解，这种裂解的变化是否对应于沃尔巴克氏体密度的变化以及与宿主的相互作用？我们提出这些主题作为替代主流观点，即噬菌体可能适应沃尔巴克氏体修改节肢动物繁殖的能力。我们的初步研究表明，它们的主要作用是捕食沃尔巴克氏体。