Intrinsic Resistance to antimicrobials in Enterococcus faecalis

描述（由申请人提供）：耐抗生素革兰氏阳性细菌，如粪肠球菌和金黄色葡萄球菌，是医院获得性感染的主要原因。粪肠杆菌是一种成功的医院获得性病原体，部分原因是它对常用的靶向细菌包膜生物发生的抗生素具有内在抗性。然而，关于粪肠杆菌内在抗菌素耐药性的遗传和生化基础的许多问题仍未得到解答。初步研究发现了一种新的信号转导系统，该系统含有真核型丝氨酸/苏氨酸激酶（PrkC），这是粪肠杆菌内在抗微生物药物耐药性所必需的。我们假设PrkC监测包膜活性抗生素引起的细胞扰动，并介导适应性生物反应以产生抗菌素耐药性。我们的长期目标是了解这个新的信号系统在介导耐药性中的作用，更广泛地说，是粪肠杆菌内在抗微生物药物耐药性的遗传和生化基础。本提案的目的是开始阐明信号转导的作用，特别是PrkC途径，介导肠球菌的内在抗菌素耐药性。为了实现这一目标，我们将：1)定义依赖于prkc的调控电路；2)确定PrkC磷酸化的直接底物；3)表征内在抗菌素耐药性的效应物（prkc依赖性信号的输出）。因此，本文提出的研究将提供新的细菌信号系统功能的见解，增强对革兰氏阳性菌抗微生物药物耐药性机制的基本理解，并为未来开发针对耐药细菌引起的感染的创新疗法奠定基础。

DESCRIPTION (provided by applicant): Antibiotic-resistant Gram-positive bacteria, such as Enterococcus faecalis and Staphylococcus aureus, are major causes of hospital-acquired infections. E. faecalis is a successful hospital-acquired pathogen partly due to its intrinsic resistance to commonly used antibiotics that target bacterial cell envelope biogenesis. However, many questions regarding the genetic and biochemical basis for intrinsic antimicrobial resistance in E. faecalis remain unanswered. Preliminary studies identified a new signal transduction system containing a eukaryotic-type Ser/Thr kinase (PrkC) that is required for intrinsic antimicrobial resistance in E. faecalis. We hypothesize that PrkC monitors the cell envelope for perturbations caused by envelope-active antibiotics and mediates an adaptive biological response to produce antimicrobial resistance. Our long-term goal is to understand the role of this new signaling system in mediating resistance, and more generally, the genetic and biochemical basis for intrinsic antimicrobial resistance in E. faecalis. The objective of this proposal is to begin to elucidate the role of signal transduction, and specifically of the PrkC pathway, in mediating intrinsic antimicrobial resistance in enterococci. To achieve this goal, we will: 1) Define the PrkC-dependent regulatory circuit; 2) Identify direct substrates for phosphorylation by PrkC; and 3) Characterize effectors of intrinsic antimicrobial resistance (the output of PrkC-dependent signaling). Thus, the research proposed here will provide insights into the function of a new bacterial signaling system, enhance fundamental understanding of the mechanisms responsible for antimicrobial resistance in Gram- positive bacteria, and form the foundation for future efforts to develop innovative therapies against infections caused by resistant bacteria. PUBLIC HEALTH RELEVANCE: Antibiotic-resistant bacteria, such as Enterococcus faecalis and Staphylococcus aureus, are major causes of hospital-acquired infections. The research proposed here will enhance fundamental understanding of the mechanisms responsible for antimicrobial resistance in Gram-positive bacteria and form the foundation for future efforts to develop innovative therapies against infections caused by resistant bacteria.