CONTROL OF AUTOLYSIS IN PNEUMOCOCCI

细菌自溶酶（细胞壁水解酶）的调节是一个重要的机制。 高度复杂的生理任务。 抗生素，如青霉素 通过干扰内源性微生物的控制来诱导细菌溶解 自溶酶，表明主要的化疗相关性 自溶素 虽然抗生素与细胞壁的结合是合成的， 酶已经被很好地表征，这是未知的， 事件导致自溶酶的失调。 正是这一方面 抗生素活性，显示为耐受 表型，即 这一提案的重点。 对青霉素有反应而停止生长但不能溶解的细菌 而死亡被称为宽容。 这种特性确保了细菌的存活 并且是大多数菌株发展的第一步， 抗生素耐药性 从机制上讲，宽容产生于 药物与细菌结合的水平（耐药位点） 出现）。 传统上，耐受性是在实验室中通过敲击来诱导的 从致命的自溶素中提取 这种生理学的大部分研究 因为它只含有一种主要的自溶酶， 这提供了一个简单的模型系统， 在自溶级联中。 临床上也描述了耐受性 分离的肺炎球菌，但耐受机制尚不清楚 由于自溶酶是存在的并且是功能性的， 在青霉素存在的情况下， 细菌。 这项建议旨在应用一种新开发的基因 鉴定控制自溶重要遗传元件策略 活动 已经建立了插入失活突变体文库， 筛选突变体，其中基因功能的丧失使 细菌耐青霉素，尽管存在正常的自溶 酵素 参与耐受表型产生的基因 将被定性。 一种特别令人感兴趣的突变体具有一种 组氨酸激酶的失活，表明可能的信号传导 这是触发裂解活性的重要途径。 非常近期 对这种突变体的分析表明，它也有天然缺陷。 DNA的转化表明了自溶 和转变。 这将提供重要的信息， 开发新的潜在抗菌剂，并可能建议 为什么临床环境中的细菌选择调节自溶 活性，而不是免除与sucidal自溶素在面对aof 抗生素压力

Regulation of bacterial autolytic enzymes (cell wall hydrolases) is a highly spohisticated physiological task. Antibiotics such as pencicillin induce bacteriolysis by interfering with the control of the endogenous autolytic enzymes, indicating the major chemotherapeutic relevance of autolysins. Although the binding of antibiotics to cell wall synthetic enzymes has been very well characterized, it is unknown how this event leads to deregulation of autolytic enzymes. It is this aspect ofantibiotic activity, revealed as the tolerant phenotype, that is the focus of this proposal. Bacteria which stop growing in response to penicillin but fail to lyse and die are termed tolerant. This property ensures bacterial survival and is the first step for most strains on the way to development of antibiotic resistance. Mechanistically, tolerance arises beyond the level of the drug binding to the vacteria (the site where resistance arises). Classically, tolerance has been induced in the lab by knock out of the lethal autolysin. Much of this physiology has been studies in pneumococci becuase it contains only one major autolytic enzyme, this providing a simple, model system from which to learn of elements in the autolytic cascade. Tolerance has also been described in clinical isolates of pneumococci, but, the mechanism of tolerance is unknown since the autolytic enzyme is present and functional but is apparently, not triggered to act in the presence of penicillin bound to the bacterium. This proposal seeks to aply a newly developed genetic strategy to identify genetic elements important in control of autolytic activity. A library of insertionally inactivated mutants has been screened for mutants in which loss of function of a gene renders the bacteria tolerant to penicillin despite the presence of normal autolytic enzyme. The genes involved in generation of the tolerant phenotype will be characterized. One mutant of particular interest harbors an inactivation in a histidine kinase, suggesting a possible signalling pathway important for the triggering of lytic activity. Very recent analysis of this mutant indicates it is also defective for natural transformation of DNA suggesting a programed link between autolysis and transformation. This will provide information important to the development of new potential antibacterial agents and perhaps suggest why bacteria in the clinical encironment choose to reggulate autolytic activity rather than dispense with sucidal autolysins in the face aof antibiotic pressure.