Role and regulation of peptidoglycan synthases in enterococcal antimicrobial resistance

项目摘要 抗生素耐药性的持续和不可避免的出现需要一个强有力的和持续的 努力从根本上确定新的目标和创新的抗菌治疗策略。 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体，部分原因是它们对常用的 针对细菌细胞包膜的抗生素，如头孢菌素。然而，许多问题 关于肠球菌中头孢菌素耐药性的遗传和生化基础， 以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-在调节头孢菌素耐药性，但 驱动头孢菌素耐药性的信号通路中的下游效应物仍然未知。 在初步研究中，我们发现两种青霉素结合蛋白-合成酶， 肽聚糖-每一种都是头孢菌素耐药性所必需的，但在功能上不同于 对方.这些青霉素结合蛋白的活性调节的机制， 肠球菌是未知的，虽然目前的模型指出，这些青霉素结合的可能性， 蛋白质作为多蛋白肽聚糖合成酶复合物的组分存在。我们的数据表明 IreK和CroS/R信号系统负责调节青霉素结合蛋白 促进头孢菌素耐药性的活性。需要解决的主要知识差距是：（一） 响应头孢菌素应激的肽聚糖酶的组成和活性是 未知;（ii）IreK或CroS/R与肽聚糖酶之间的明确联系尚未确定。 建立;和（iii）头孢菌素诱导致死的机制，当一个 肽聚糖合酶受损的情况尚不清楚。这里提出的研究旨在阐明 对肽聚糖酶在生物过程中的作用和调节的新见解， 导致肠球菌对头孢菌素产生耐药性。通过这样做，我们将提供新的见解 驱动肠球菌中关键抗生素耐药性的基本生物学过程， 创新疗法的目标，旨在削弱肠球菌头孢菌素耐药性。

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.