Impact of nucleotide metabolism on enterococcal antibiotic resistance

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，部分原因是它对针对细菌细胞包膜的常用抗生素具有耐药性。然而，粪肠杆菌这种抗菌素耐药性的遗传和生化基础尚不清楚。初步研究确定了许多参与影响粪肠杆菌抗菌素耐药性的核苷酸代谢的基因。这些观察结果表明，细胞内核苷酸水平在导致抗生素耐药性的细胞过程调节中起着关键的、尚未被认识的作用。我们的长期目标是了解细胞内核苷酸在抗生素耐药中的生物学和生化作用，更广泛地说，了解粪肠杆菌耐药的整体遗传和生化基础。本提案的目的是确定哪些特定的核苷酸影响耐药性，并开始阐明核苷酸如何通过识别编码在粪肠球菌基因组中的核苷酸反应因子来发挥其对耐药性的影响。为了实现这一目标，我们将：1)通过测量显示头孢菌素耐药性改变的突变体的核苷酸水平，确定粪肠杆菌中核苷酸水平与头孢菌素耐药性的关系；2)利用无偏见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反应效应物。通过实现这些目标，本文提出的研究将深入了解核苷酸在粪肠球菌细胞过程调控中的作用，增强对革兰氏阳性细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 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.