CONTROL OF AUTOLYSIS IN PNEUMOCOCCI

细菌自溶酶(细胞壁水解酶)的调节是一种 高度间歇性的生理任务。抗生素，如盘尼西林 通过干扰内源性细菌的控制而诱导细菌溶解 自溶酶，表明主要的化疗相关性 自溶素。尽管抗生素与细胞壁合成的结合 酶已经被很好地表征了，还不知道这是如何 这一事件导致自溶酶的解除管制。就是这方面 的抗生素活性，表现为耐受表型，即 这项提案的重点。 对青霉素有反应但不能溶解的细菌 和死亡被称为宽容。这一特性确保了细菌的存活 这是大多数菌株在发展的道路上的第一步 抗生素耐药性。从机制上讲，容忍度超越了 药物与空肠(耐药部位)结合的水平 产生)。传统上，耐受性是在实验室中通过敲门诱导出来的 从致命的自溶素中排出。这种生理学的大部分已经被研究过了。 在肺炎球菌中，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，从中可以学习元素 在自溶级联中。耐受性也已在临床上得到了描述 肺炎球菌的分离株，但耐药机制尚不清楚 由于自溶酶存在并具有功能，但显然， 在青霉素结合的情况下未被触发的行为 细菌。这项建议旨在应用一种新开发的基因 确定控制自溶的重要遗传因素的策略 活动。插入失活突变体的文库已经 筛选基因功能丧失的突变体 尽管存在正常的自溶，但对青霉素耐药的细菌 酵素。与耐性表型产生有关的基因 将被描述为。一个特别感兴趣的突变体藏匿着一种 组氨酸激酶失活，暗示可能的信号 对激活溶血活性很重要的途径。非常近 对这个突变体的分析表明，它也是天然的缺陷 DNA的转化表明自溶作用之间存在程序性联系 和转型。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 而不是在面对AOF时放弃自溶素 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.