Inducible Antibiotic Resistance in Methicillin-Resistant Staphylococcus Aureus

耐甲氧西林金黄色葡萄球菌诱导的抗生素耐药性

• 批准号: 8479497
• 负责人: Shahriar Mobashery
• 金额: $ 40.04万
• 依托单位: UNIVERSITY OF NOTRE DAME
• 依托单位国家: 美国
• 财政年份: 2013
• 资助国家: 美国
• 起止时间: 2013-01-01 至 2017-12-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8479497
• 关键词: Active Sites; Allosteric Site; Antibiotic Resistance; Antibiotics; Applications Grants; Binding; Binding Sites; Carbapenems; Cell Wall; Cephalosporins; Clinical; Complex; Cytoplasmic Tail; Decarboxylation; Development; Evaluation; Event; Exposure to; Gene Proteins; Generations; Genes; Heel; Infection; Knowledge; Lactamase; Lead; Left; Lysine; Membrane; Modification; Molecular; Monobactams; Organism; Penicillin-Binding Proteins; Penicillins; Phosphorylation; Physiological; Process; Protein Inhibition; Proteins; Resistance; Role; Scourge; Series; Serine; Signal Transduction; Study Subject; Surface; System; Time; Transducers; Tyrosine Phosphorylation; Work; carboxylate; crosslink; expectation; experience; killings; meetings; member; methicillin resistant Staphylococcus aureus; public health relevance; resistance mechanism; sensor

DESCRIPTION (provided by applicant): Methicillin-resistant Staphylococcus aureus (MRSA) has acquired an inducible resistance mechanism to ¿- lactam antibiotics that encompasses essentially all members of the antibiotic class. This resistance is conferred by a set of genes that encode an antibiotic sensor/signal transducer protein, gene repressor and two resistant determinants, a class A ¿-lactamases and a special penicillin-binding protein (PBP) referred to as PBP2a. We have documented that the antibiotic sensor/signal transducer protein BlaR1 experiences covalent modification by ¿-lactam antibiotics in its membrane-surface domain, which through a unique process that we have termed "lysine N-decarboxylation switch" activates the protein for signal transduction across the membrane. Subsequent to this event, the cytoplasmic domain of BlaR1 experiences phosphorylation, all within the time frame relevant to induction of resistance. The elucidation of the importance of this BlaR1 phosphorylation to the antibiotic resistance events is the subject of study under Specific Aim 1. PBP2a performs cross-linking of the cell wall in MRSA, a function that is indispensible to its survival. PBP2a is not inhibited well by ¿-lactam antibiotics as it has a closed active site, hence its function in resistance. We have elucidated an allosteric site on this protein that is triggered to facilitate opening of the active site for the physiological role of the protein. The allosteric site is an Achiles' Heel of PBP2a, since its triggering for the opening of the active site would leave the protein (and MRSA) vulnerable to ¿-lactam antibiotics that have met their obsolescence in treatment of infections by MRSA. In Specific Aim 2 we propose to investigate how this protein performs its physiological role and how its processes can be subverted in devising new strategies in treatment of MRSA infections. Furthermore, we propose to study antibiotic resistance mechanisms that arise by alterations in the allosteric site.

描述（由申请人提供）：耐甲氧西林金黄色葡萄球菌（MRSA）已经获得了对β-内酰胺抗生素的诱导耐药机制，该机制基本上涵盖了抗生素类别的所有成员。这种耐药性是由一组编码抗生素传感器/信号转导蛋白、基因阻遏物和两个耐药决定簇的基因赋予的，即 A 类 β-内酰胺酶和称为 PBP2a 的特殊青霉素结合蛋白 (PBP)。我们已经记录了抗生素传感器/信号转导蛋白 BlaR1 在其膜表面结构域中经历了 β-内酰胺抗生素的共价修饰，通过我们称为“赖氨酸 N-脱羧开关”的独特过程激活蛋白质进行跨膜信号转导。在此事件之后，BlaR1 的胞质结构域经历磷酸化，所有这些都在与诱导耐药性相关的时间范围内发生。阐明 BlaR1 磷酸化对抗生素耐药事件的重要性是特定目标 1 下的研究主题。PBP2a 在 MRSA 中执行细胞壁的交联，这是其生存不可或缺的功能。 PBP2a 不能被β-内酰胺抗生素很好地抑制，因为它具有封闭的活性位点，因此具有耐药性。我们已经阐明了该蛋白质上的变构位点，该变构位点被触发以促进活性位点的打开以发挥蛋白质的生理作用。变构位点是 PBP2a 的致命弱点，因为它触发活性位点的打开会使蛋白质（和 MRSA）容易受到β-内酰胺抗生素的影响，而这些抗生素在治疗 MRSA 感染时已经过时了。在具体目标 2 中，我们建议研究这种蛋白质如何发挥其生理作用，以及如何在设计治疗 MRSA 感染的新策略时颠覆其过程。此外，我们建议研究变构位点改变引起的抗生素耐药机制。