Mechanisms of host-parasite interactions between bacteriophages and Erwinia amylovora

微生物多样性和细菌在生态系统功能中的作用很大程度上受到与噬菌体相互作用的影响。这些相互作用可能是复杂的，但在最基本的水平上是单个噬菌体攻击和在单个细菌内繁殖的能力。这种能力是由细菌基因组编码的组件，如表面受体和几个防御系统，并由噬菌体基因组决定的。这项拟议的研究涉及攻击淀粉欧文氏菌和聚集性欧文氏菌的噬菌体基因的研究，以期在宿主发病中做出贡献。我们最近对19个噬菌体的基因组进行了测序，这些噬菌体与几个寄主物种的相互作用是不同的。观察到的噬菌体与淀粉菌之间的相互作用包括与后代产生的裂解反应，裂解反应和假性裂解反应，或没有明显的攻击。这些序列信息是了解噬菌体攻击中所有这些变异的基因控制的宝贵资源。这项研究的具体短期目标将涉及：(1)噬菌体基因与宿主攻击中的变异的关联和这些基因的注释；(2)通过特定细菌宿主重复传代噬菌体进行协同进化实验，以寻找/选择改变的相互作用，并观察(1)中确定的基因的任何突变变化；以及(3)人工诱导导致与宿主相互作用改变的噬菌体突变，并将这些突变与(1)中确定的基因联系起来。长期目标将包括宿主编码的属性与这些噬菌体成分的相关性。这项拟议研究的预期意义是，我们将确定噬菌体攻击的各种分子机制，并最终确定所有这些观察到的变异如何影响微生物多样性和种群动态。

Microbial diversity and the roles of bacteria in the function of ecosystems are greatly influenced by interactions with bacteriophages. These interactions can be complex but at the most basic level is the ability of an individual bacteriophage to attack and multiply within a single bacterium. This ability is determined by the bacterial genome encoding components such as surface receptors and several defense systems, and by the bacteriophage genome. The proposed research involves investigation of the genes of bacteriophages that attack the bacterial species, Erwinia amylovora and Pantoea agglomerans, for contributions to host pathogenesis. We have recently sequenced the genomes of nineteen bacteriophages that are individually variable in interaction with several host species. Observed interactions between the bacteriophages and E. amylovora include lysis with progeny production that varies over four orders of magnitude, lysogeny, and pseudolysogeny, or no apparent attack whatsoever. This sequence information is a valuable resource for understanding the genetic control of all of this variation in bacteriophage attack. Specific short term objectives of this research will involve: (1) correlation of bacteriophage genes with variation in host attack and annotation of these genes; (2) co-evolution experiments with repeated passages of the bacteriophages through a specific bacterial host to look/select for altered interaction and to observe any mutational changes in the genes identified in (1); and, (3) to artificially induce mutations in bacteriophages that result in altered interaction with the host and to relate these mutations to the genes identified in (1). Long term objectives will include correlation of host-encoded attributes with these bacteriophage components. The expected significance of the proposed research is that we shall identify various molecular mechanisms of bacteriophage attack and ultimately how all of this observed variation impacts on microbial diversity and population dynamics.