Expansion of enterococcal insertion sequence elements during bacteriophage infection

项目摘要 多重耐药肠球菌感染是一个严重的公共卫生威胁。肠球菌，包括 粪肠球菌通常对关键的一线药物如氨苄青霉素和/或万古霉素具有耐药性。 由于目前可用的药物治疗肠球菌感染的难度越来越大， 需要治疗方案。一种可能性是利用细菌病毒进行治疗， 噬菌体（bacteriophagens）。虽然噬菌体治疗在临床上显示出希望，但噬菌体的出现并不意味着噬菌体治疗的成功。 细菌中的抗性是未来噬菌体疗法的严重问题。为了克服这一点，我们需要 了解细菌如何在遗传水平上对噬菌体感染作出反应，以及 噬菌体抗性本实验室过去的工作发现，E.抗裂解性噬菌体19（phi 19）的粪杆菌分离株 感染后，其基因组中IS 256转座因子插入数量增加。这些 在噬菌体感染相关基因中普遍发现插入，表明phi 19感染 刺激IS 256转座以产生新的遗传组合，导致噬菌体抗性。我 初步工作已经证明phi 19感染激活IS 256动员。我发现phi 19 感染增加了IS 256转座酶的翻译，而phi 19编码的转录因子， 类似于抗σ因子，称为PAS 19，增加IS 256转座酶翻译。这表明 PAS 19负责在phi 19感染期间激活IS 256。这个项目的目标是破译 急诊faecalis基因组响应于噬菌体驱动的IS 256激活而进化，以及这些下游基因组是如何进化的。 影响可以告知噬菌体治疗策略。为了实现这些目标，我将执行两个具体目标： 1.建立了噬菌体诱导的IS 256插入在E.粪便工作 将证明噬菌体介导的功能性酶促需要和时机 IS 256激活，并将确定这种活性是否广泛适用于不同的肠球菌感染;目的2： 确定一个假定的噬菌体转录因子如何控制IS 256激活。PAS 19，一种假定的 由phi 19编码的转录因子激活IS 256表达。在这个目标中，我将描述PAS 19 控制IS 256基因的激活。

PROJECT SUMMARY Multidrug resistant enterococcal infections are a serious public health threat. The enterococci, including Enterococcus faecalis, often harbor resistance to critical front-line drugs such as ampicillin and/or vancomycin. Due to the increasing difficulty of treating enterococcal infections with currently available drugs, alternative treatment options are needed. One possibility is the therapeutic use of bacterial viruses known as bacteriophages (phages). While phage therapy has shown promise in the clinic, the emergence of phage resistance in bacteria is a serious concern for future phage therapies. To overcome this, we need to understand how bacteria respond to phage infection at the genetic level and the physiological consequences of phage resistance. Past work in our lab discovered that E. faecalis isolates resistant to lytic phage 19 (phi19) infection harbored an increased number of IS256 transposable element insertions in their genomes. These insertions were commonly found in genes involved in phage infection, suggesting that phi19 infection stimulates IS256 transposition to create new genetic combinations, leading to phage resistance. My preliminary work has demonstrated that phi19 infection activates IS256 mobilization. I have found that phi19 infection increases the translation of the IS256 transposase, and that a phi19-encoded transcription factor that resembles an anti-sigma factor, termed PAS19, increases IS256 transposase translation. This indicates that PAS19 is responsible for activating IS256 during phi19 infection. The goals of this project are to decipher how the E. faecalis genome evolves in response to phage driven IS256 activation, and how these downstream effects can inform phage therapeutic strategies. To achieve these goals, I will execute two specific aims: Aim 1: Establish a mechanistic basis for phage-induced expansion of IS256 insertions in E. faecalis. Work performed in this aim will demonstrate the functional enzymatic requirements and timing of phage mediated IS256 activation, and will determine if this activity is broadly applicable to diverse enterococcal phages; Aim 2: Determine how a putative phage transcription factor controls IS256 activation. PAS19, a putative transcription factor encoded by phi19 activates IS256 expression. In this aim, I will delineate how PAS19 controls IS256 gene activation.