Role and regulation of a peptidoglycan synthesis enzyme required for cephalosporin resistance in enterococci

项目摘要/摘要： 感染性心内膜炎是一种细菌在心脏瓣膜上以类似生物膜的状态生长的情况，是一种 血液感染的致命并发症。肠球菌占医疗保健的30%- 获得性心内膜炎。当由多重耐药菌株引起时，如耐万古霉素的肠球菌 感染性心内膜炎(VRE)几乎是无法治疗的，而且几乎都是致命的。疾控中心认为VRE是一个严重的威胁 并估计2017年与VRE相关的死亡人数为5400人，相关医疗成本超过5亿美元。一位少校 肠球菌性心内膜炎和其他感染的危险因素是事先接受过 头孢菌素类抗生素。临床上最相关的两种肠球菌，粪肠球菌和粪肠球菌， 对头孢菌素有内在的抗药性。头孢菌素类抗生素治疗允许共生 肠球菌繁殖并扩散到血液中，这是心脏瓣膜感染的先决条件。 本项目的目的是为了进一步了解头孢菌素耐药的分子机制。 肠球菌。这一认识将使新疗法的开发既能减少糖尿病的发生 肠球菌感染和改进治疗方案以克服顽固性心内膜感染。 具体地说，将研究两个已知的头孢菌素耐药决定因素Irek之间的新联系 还有穆拉。Irek是一种被认为可以感知细胞壁压力并对其做出反应的激酶，包括由 肽聚糖交联对头孢菌素治疗的抑制作用。然而，艾瑞克的目标发出了信号 促进这一反应，并最终头孢菌素耐药性，在很大程度上是未知的。Muraa，一种可以 催化合成肽聚糖的第一步也是头孢菌素耐药所必需的。这个 该项目的中心假设是Muraa是IREK信号的下游靶点，因此调节 MuraA是Irek控制头孢菌素耐药性的一种机制。初步证据表明 这种调节是由已知的Irek-磷酸化底物IreB介导的。这一假设将会得到解决。 有两个目标。目标1将确定IreB和Irek信号如何影响MuraA的功能。目标2将确定 Muraa互动伙伴，并确定这些互动的功能后果。初步数据 提示蛋白质之间的相互作用对于促进或调节MuraA的功能是重要的。 这项工作将在克里斯托弗·克里斯蒂奇博士的赞助下在威斯康星州医学院进行。这个 赞助商和机构都有能力为这次奖学金提供资源和支持。在协作中 在赞助商的帮助下，应聘者设计了一个培训计划来补充这个项目。培训计划 支持发展广泛的技术、沟通和指导技能，并鼓励专业人员 候选人的发展。这些能力的发展将促进职业生涯的成功 作为一名全面发展的独立科学家，研究人类健康和疾病中的微生物。

PROJECT SUMMARY/ABSTRACT: Infective endocarditis, a condition in which bacteria grow in a biofilm-like state on the valves of the heart, is a deadly complication of bloodstream infections. Enterococcus species are responsible for 30% of healthcare- acquired endocarditis. When caused by multi-drug resistant strains, such as vancomycin-resistant enterococci (VRE), infective endocarditis is nearly untreatable and uniformly fatal. The CDC considers VRE a serious threat and estimates 5,400 VRE-related deaths and over $500 million in associated healthcare costs in 2017. A major risk factor for the development of enterococcal endocarditis and other infections is prior treatment with cephalosporin antibiotics. The two most clinically relevant species of Enterococcus, E. faecalis and E. faecium, are intrinsically resistant to cephalosporins. Treatment with cephalosporin antibiotics allows commensal enterococci to proliferate and disseminate to the bloodstream, a prerequisite for infection of the heart valves. The goal of this project is to further our understanding of molecular mechanisms of cephalosporin resistance in enterococci. This understanding will enable development of new therapies that both reduce the occurrence of enterococcal infections and improve treatment options to overcome recalcitrant endocardial infections. Specifically, a novel link will be investigated between two known cephalosporin resistance determinants, IreK and MurAA. IreK is a kinase that is thought to sense and respond to cell wall stress, including that caused by inhibition of peptidoglycan crosslinking upon cephalosporin treatment. However, the targets of IreK signaling that facilitate this response, and ultimately cephalosporin resistance, are largely unknown. MurAA, an enzyme that catalyzes the first committed step in peptidoglycan synthesis is also required for cephalosporin resistance. The central hypothesis of this project is that MurAA is a downstream target of IreK signaling, such that regulation of MurAA is one mechanism by which IreK controls cephalosporin resistance. Preliminary evidence suggests that this regulation is mediated by the known IreK-phosphorylation substrate, IreB. This hypothesis will be addressed in two aims. Aim 1 will determine how IreB and IreK signaling impact functions of MurAA. Aim 2 will identify MurAA interaction partners and determine the functional consequences of these interactions. Preliminary data suggest that a protein-protein interaction is important for either facilitating or regulating functions of MurAA. This work will be conducted at the Medical College of WI under the sponsorship of Dr. Christopher Kristich. The sponsor and institution are well-equipped to provide resources and support for this fellowship. In collaboration with the sponsor, the candidate has designed a training plan that complements this project. The training plan supports development of broad technical, communication and mentoring skills and encourages the professional development of the candidate. Development of these competencies will catalyze a successful career for the candidate as a well-rounded, independent scientist investigating microbes in human health and disease.