Impact of nucleotide metabolism on enterococcal antibiotic resistance

描述（由申请方提供）：耐抗生素的革兰氏阳性菌，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。E.粪肠球菌是一种成功的医院获得性病原体，部分原因是其对靶向细菌细胞包膜的常用抗生素具有抗性。然而，这种耐药性的遗传和生化基础，在大肠杆菌。对粪杆菌知之甚少。初步研究确定了许多参与核苷酸代谢的基因，这些基因影响大肠杆菌的抗菌素耐药性。粪便这些观察结果表明，细胞内核苷酸水平在调节导致抗生素耐药性的细胞过程中起着关键的、尚未被认识到的作用。我们的长期目标是了解细胞内核苷酸在抗生素耐药性中的生物学和生化作用，更一般地说，是大肠杆菌耐药性的整体综合遗传和生化基础。粪便本研究的目的是确定哪些特定的核苷酸影响抗性，并通过鉴定大肠杆菌中编码的核苷酸应答因子来开始阐明核苷酸如何对抗性发挥作用。faecalis基因组为了实现这一目标，我们将：1）确定核苷酸水平与大肠杆菌头孢菌素耐药性的关系。通过测量突变体中表现出改变的头孢菌素耐药性的核苷酸水平来检测粪肠球菌;和2）利用无偏倚的全基因组遗传策略来鉴定影响头孢菌素耐药性的核苷酸应答效应物。通过实现这些目标，本文提出的研究将提供深入了解核苷酸在调节大肠杆菌细胞过程中的作用。粪肠球菌，增强对革兰氏阳性菌抗菌素耐药性机制的基本理解，并为未来开发针对耐药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 in part because of its resistance to commonly used antibiotics that target the bacterial cell envelope. However, the genetic and biochemical basis for this antimicrobial resistance in E. faecalis is poorly understood. Preliminary studies identified numerous genes involved in nucleotide metabolism that influence antimicrobial resistance in E. faecalis. These observations suggest that intracellular nucleotide levels are playing critical, as-yet-unappreciated roles in regulation of cellular processes leading to antibiotic resistance. Our long-term goal is to understand the biological and biochemical roles of intracellular nucleotides in antibiotic resistance, and more generally, the overall integrated genetic and biochemical basis for antimicrobial resistance in E. faecalis. The objective of this proposal is to define which specific nucleotides influence resistance, and to begin elucidating how nucleotides exert their effect on resistance by identifying nucleotide-responsive factors encoded in the E. faecalis genome. To achieve this goal, we will: 1) Define the relationship of nucleotide levels to cephalosporin resistance in E. faecalis by measuring nucleotide levels in mutants exhibiting altered cephalosporin resistance; and 2) Exploit unbiased, genome-wide genetic strategies to identify nucleotide-responsive effectors that influence cephalosporin resistance. By achieving these aims, the research proposed here will provide insights into the role of nucleotides in regulation of cellular processe in E. faecalis, enhance fundamental understanding of 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.