Discovery and characterization of bacterial cell envelope assembly and remodeling networks that modulate tolerance to antibiotics

调节抗生素耐受性的细菌细胞包膜组装和重塑网络的发现和表征

• 批准号: 10711329
• 负责人: Josue Flores-Kim
• 金额: $ 41.88万
• 依托单位: UNIV OF MASSACHUSETTS MED SCH WORCESTER
• 依托单位国家: 美国
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-07-01 至 2028-04-30
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10711329
• 关键词: Affect; Antibiotics; Bacteria; Bacterial Physiology; Biogenesis; Biological Models; Cell Enlargement; Cell Shape; Cell Wall; Cell division; Cells; Cellular Morphology; Complex; Cytolysis; Enzymes; Equilibrium; Goals; Growth; Health; Human; Infection; Laboratories; Link; Maintenance; Membrane; Molecular; Multi-Drug Resistance; N-Acetylmuramoyl-L-alanine Amidase; Osmosis; Pathogenesis; Pathway interactions; Peptide Hydrolases; Peptidoglycan; Physiological; Polymers; Post-Translational Protein Processing; Process; Proteolysis; Regulation; Research; Role; Signal Transduction; Streptococcus pneumoniae; Structure; System; Teichoic Acids; Therapeutic Intervention; Virulence; antibiotic tolerance; cell envelope; cell growth; insight; lipoteichoic acid; model organism; new therapeutic target; novel; pathogen; respiratory pathogen; therapeutic development

Abstract The bacterial cell envelope is a complex and dynamic multilayered structure essential for cell growth and division. The structural layer of the envelope, known as the cell wall or peptidoglycan (PG), determines cell shape and is essential for survival because it protects bacteria from osmotic lysis. The action of PG synthases, which add new material for the enlargement of the cell wall, and PG hydrolases, which create space for expansion of the PG mesh-like structure, are both necessary for growth. Some of our most powerful and successful antibiotics target PG synthases and derive their efficacy from not only inhibiting cell wall assembly, but also by causing cell lysis through the active destruction of the cell wall by PG hydrolases. Because of their potential to cause cell lysis, it has long been appreciated that bacteria must possess robust mechanisms to control when and where PG hydrolases are activated. However, the molecular details underlying these regulatory processes are lacking. Research in my laboratory focuses on uncovering and characterizing regulatory systems controlling PG hydrolase activity during normal growth, and how antibiotics short-circuit this regulation to trigger cell lysis. Using the human respiratory pathogen Streptococcus pneumoniae as a model organism, we found that PG hydrolases are controlled by two cell envelope polymers known as teichoic acids (TAs): membrane-linked lipoteichoic acids (LTAs) and cell wall-anchored teichoic acids (WTAs). Characterization of novel enzymes involved in TA synthesis and remodeling revealed that cell-wall targeting antibiotics hyperactivate PG hydrolases by disrupting the normal mechanisms that balance the levels of WTAs and LTAs in the cell envelope. Current studies in my laboratory indicate that the levels of TAs are controlled by a complex regulatory network involving post- translational modifications and targeted proteolysis. We also discovered that the modulation of the TA levels in the cell envelope has significant impacts on cell morphology, growth, and tolerance to antibiotics. However, many aspects of this regulation and synthesis and remodeling pathways remain unknown. Therefore, the goals of this proposal are to (i) identify signals and pathways that modulate LTA biogenesis and characterize how antibiotics subvert them; (ii) determine the physiological roles and regulation of a widely-conserved protease and characterize how antibiotics hyperactivate its activity to disrupt LTA biogenesis; (iii) characterize the regulation of a novel WTA remodeling enzyme, and uncover how S. pneumoniae uses WTA levels to control lysis and promote growth. The results generated by this research will provide fundamental insights into broadly relevant principles for envelope assembly and maintenance in S. pneumoniae and related bacteria. S. pneumoniae has become an alarming multidrug-resistant health threat. Therefore, novel antibiotics that target S. pneumoniae are critically needed. The studies proposed here will reveal general mechanisms by which bacteria remodel their envelopes to survive antibiotic exposure and uncover new targets for therapeutic intervention.

摘要 细菌细胞被膜是一种复杂且动态的多层结构，对于细胞生长和分裂至关重要。 被膜的结构层，称为细胞壁或肽聚糖（PG），决定了细胞的形状， 对于生存至关重要，因为它可以保护细菌免受渗透溶解。PG酶的作用，增加了新的 用于扩大细胞壁的材料，以及PG水解酶，其为PG的扩展创造空间 网状结构，都是生长所必需的。一些最有效和最成功的抗生素靶向 PG降解酶，其功效不仅来自于抑制细胞壁组装，还来自于引起细胞裂解 通过PG水解酶对细胞壁的主动破坏。由于它们可能导致细胞溶解， 长期以来，人们一直认为细菌必须拥有强大的机制来控制何时何地PG 水解酶被激活。然而，这些调控过程背后的分子细节是缺乏的。 我实验室的研究重点是揭示和表征控制PG的调节系统 在正常生长过程中水解酶的活性，以及抗生素如何使这种调节短路从而引发细胞裂解。使用 以人类呼吸道病原体肺炎链球菌为模式生物，我们发现PG水解酶 由两种被称为磷壁酸（TA）的细胞包膜聚合物控制：膜连接脂磷壁酸 （LTA）和细胞壁锚定磷壁酸（WTA）。TA相关的新酶的表征 合成和重塑揭示了细胞壁靶向抗生素通过破坏PG水解酶， 平衡细胞包膜中WTA和LTA水平的正常机制。我目前的研究 实验室表明，TA的水平是由一个复杂的调控网络控制的， 翻译修饰和靶向蛋白水解。我们还发现， 细胞被膜对细胞形态、生长和对抗生素的耐受性具有显著影响。但不少 这种调节和合成以及重塑途径的各个方面仍然是未知的。因此，这一目标 建议是（i）确定调节LTA生物发生的信号和途径，并表征抗生素如何 （ii）确定广泛保守的蛋白酶的生理作用和调节，以及 表征抗生素如何过度激活其活性以破坏LTA生物合成;（iii）表征调节 一种新的WTA重塑酶，并揭示如何S。肺炎克雷伯氏菌使用WTA水平来控制裂解， 促进增长。这项研究产生的结果将提供广泛相关的基本见解 在S.肺炎和相关细菌。S.肺炎有 成为令人担忧的多重耐药健康威胁。因此，针对S.肺炎是 急需的。这里提出的研究将揭示细菌重塑其细胞的一般机制。 信封，以生存抗生素暴露和发现新的目标，治疗干预。