Role and regulation of peptidoglycan synthases in enterococcal antimicrobial resistance

项目总结 抗生素耐药性的持续和不可避免的出现需要强有力和持续的 努力从根本上确定创新抗菌疗法的新目标和战略。 耐药肠球菌是医院获得性感染的主要原因。肠球菌是 成功的医院获得性病原菌部分原因是他们对常用药物的内在抗药性 针对细菌细胞膜的抗生素，如头孢菌素。然而，许多问题 关于肠球菌对头孢菌素耐药的遗传和生化基础仍然存在。 先前的工作揭示了两个信号转导系统的关键作用--Irek跨膜 激酶和CROS/R双组分系统-在头孢菌素耐药的调节中，但 驱动头孢菌素耐药的信号通路中的下游效应器仍不清楚。 在初步研究中，我们发现了两种青霉素结合蛋白--合成青霉素的酶 肽聚糖-每种都是头孢菌素耐药所必需的，但在功能上与 彼此之间。这些青霉素结合蛋白的活性被调节的机制 肠球菌是未知的，尽管目前的模型表明这些青霉素结合的可能性 蛋白质以多蛋白肽聚糖合成酶复合体的形式存在。我们的数据显示 Irek和CROS/R信号系统负责青霉素结合蛋白的调节 促进头孢菌素耐药性的活性。需要解决的主要知识差距是：(I) 对头孢菌素应激反应的肽聚糖合成酶的组成和活性如下 未知；(Ii)Irek或CROS/R与肽聚糖合成酶之间的确切联系尚未得到证实 建立；以及(Iii)头孢菌素在以下情况下导致致死的机制 肽多聚糖合成酶是否受损尚不清楚。这里提出的研究旨在阐明 对肽聚糖合成酶在生物过程中的作用和调节的新见解 引起肠球菌头孢菌素耐药。通过这样做，我们将对 驱动肠球菌关键抗生素耐药性并定义新的 旨在削弱肠球菌头孢菌素耐药性的创新疗法的目标。

PROJECT SUMMARY The continued and inevitable emergence of antibiotic resistance demands a vigorous and sustained effort to identify fundamentally new targets and strategies for innovative antimicrobial therapeutics. Antibiotic-resistant enterococci are major causes of hospital-acquired infections. Enterococci are successful hospital-acquired pathogens in part because of their intrinsic resistance to commonly used antibiotics that target the bacterial cell envelope, such as cephalosporins. However, many questions remain regarding the genetic and biochemical basis for cephalosporin resistance in enterococci. Previous work revealed key roles for two signal transduction systems - the IreK transmembrane kinase and the CroS/R two-component system - in regulation of cephalosporin resistance, but the downstream effectors in the signaling pathways that drive cephalosporin resistance remain unknown. In preliminary studies we showed that two penicillin-binding proteins – enzymes that synthesize peptidoglycan – are each essential for cephalosporin resistance, yet are functionally distinct from each other. The mechanisms by which the activity of these penicillin-binding proteins are regulated in enterococci are unknown, although current models point to the possibility that these penicillin-binding proteins exist as components of multiprotein peptidoglycan synthase complexes. Our data suggest that the IreK and CroS/R signaling systems are responsible for regulation of penicillin-binding protein activity to promote cephalosporin resistance. The major knowledge gaps to be addressed are that (i) the composition and activity of the peptidoglycan synthases in response to cephalosporin stress are unknown; (ii) a definitive link between IreK or CroS/R and the peptidoglycan synthases has not been established; and (iii) the mechanisms by which cephalosporins induce lethality when one peptidoglycan synthase is impaired is unknown. The research proposed here is designed to elucidate new insights into the roles and regulation of peptidoglycan synthases in the biological processes that drive enterococcal cephalosporin resistance. By doing so, we will provide new insights into the fundamental biological processes that drive key antibiotic resistance in enterococci and define new targets for innovative therapeutics designed to impair enterococcal cephalosporin resistance.