Serine/threonine kinase signaling in beta-lactam resistance of Staphylococcus aureus

项目摘要： 我们已经确定了真核生物样丝氨酸/苏氨酸激酶（eSTK）信号通路在细胞凋亡中的新作用。 介导耐甲氧西林金黄色葡萄球菌（MRSA）的广谱β-内酰胺耐药性。 广谱β-内酰胺耐药性使大多数β-内酰胺类药物治疗无效， 经典地通过编码青霉素结合蛋白2a的基因mecA介导。广谱 S.金黄色葡萄球菌也通过与mecA不直接相关的非经典介质发生。 非经典介体在β-内酰胺耐药中所起的作用仅得到表面上的理解。两个Stk 1 和Stp 1（eSTK信号传导的效应物;丝氨酸/苏氨酸激酶和磷酸酶）介导β-内酰胺敏感性 分别通过功能丧失或过度表达，而功能性Stk 1和非功能性Stp 1有利于药物 阻力我们的研究结果表明，eSTK通过控制mecA的途径调节β-内酰胺耐药性 表达和通过未知的非经典介质独立调节Stk 1和Stp 1。 社区MRSA菌株（以及许多医院菌株）中的mecA表达受BlaR 1- BlaI调节通路。mecA的表达通常受到转录抑制因子BlaI的抑制。 β-内酰胺类药物的存在由BlaR 1（一种整合的膜蛋白）感知。随后，BlaR 1经历 一种位点特异性的自动蛋白水解，将其细胞内锌金属蛋白酶（ZnMP）结构域释放到细菌中 胞质液释放的ZnMP降解BlaI以解除mecA表达的抑制，导致耐药性。我们的数据 显示eSTK介导BlaR 1磷酸化对于有效的mecA诱导是重要的。 通过传代研究，我们已经确定了补偿机制，使细菌， 克服上述Stk 1功能丧失或Stp 1过表达引起的药物敏感性。基因组 为破译传代菌株耐药性基础而进行的测序研究表明， 与mecA无关的途径。 提出了三个目的：a）破译eSTK控制mecA表达的机制，B） 鉴定赋予非经典β-内酰胺耐药的eSTK介体，和c）研究代偿性β-内酰胺耐药。 抗性传代菌株的抗性基础。 我们的研究将有助于确定Stk 1和Stp 1控制β-内酰胺耐药性的机制， 可以帮助确定新的和改进的治疗选择S。金黄色葡萄球菌感染

Project Abstract: We have identified novel roles of the eukaryotic-like serine/threonine kinase (eSTK) signaling pathway in mediating broad-spectrum β-lactam resistance in methicillin-resistant Staphylococcus aureus (MRSA). Broad-spectrum β-lactam resistance, which renders most β-lactam drugs therapeutically ineffective, is classically mediated through mecA, the gene that encodes penicillin-binding protein 2a. Broad-spectrum resistance to β-lactams in S. aureus also occurs through non-classical mediators not directly related to mecA. The role played by the non-classical mediators in β-lactam resistance is only superficially understood. Both Stk1 and Stp1 (effectors of eSTK signaling; a serine/threonine kinase and phosphatase), mediate β-lactam sensitivity by loss of function or overexpression respectively, whereas functional Stk1 and non-functional Stp1 favor drug resistance. Our results show that eSTK modulates β-lactam resistance via pathways controlling mecA expression and through unknown non-classical mediators independently regulated by Stk1 and Stp1. mecA expression in community MRSA strains (and many hospital strains as well) is regulated by the BlaR1- BlaI regulatory pathway. Expression of mecA is normally suppressed by the transcriptional repressor, BlaI. Presence of β-lactam drugs is sensed by BlaR1, an integral membrane protein. Subsequently, BlaR1 undergoes a site-specific auto-proteolysis releasing its intracellular zinc metalloprotease (ZnMP) domain into the bacterial cytosol. The released ZnMP degrades BlaI to de-repress mecA expression, leading to drug resistance. Our data show that eSTK mediated phosphorylation of BlaR1 is important for efficient mecA induction. Through passaging studies, we have identified compensatory mechanisms that enable the bacteria to overcome drug sensitivity due to Stk1 loss of function or Stp1 overexpression, mentioned above. Genome sequencing studies carried out to decipher the basis of resistance in passaged strains indicated involvement of pathways that are unrelated to mecA. Three aims are proposed: a) to decipher the mechanism through which eSTK controls mecA expression, b) to identify eSTK mediators that confer non-classical β-lactam resistance, and c) to investigate the compensatory basis of resistance among resistant passaged strains. Our study will help determine the mechanism/s through which Stk1 and Stp1 control β-lactam resistance and could help to identify novel and improved treatment options for S. aureus infections.