Study on signal transduction and involvement of protein synthesis machinery in the production of Bacilhus subtilis proteass

自然界中的微生物表现出多种多样的生活方式。枯草芽孢杆菌（Bacillussubtilis）是一种土壤细菌，它能在营养缺乏、干燥、温度剧烈变化等环境胁迫下生存，并能通过多种途径科普这些不利条件。例如，针对营养缺乏症，它分泌蛋白酶和降解酶来消化细胞周围碰巧存在的高分子量蛋白质或碳水化合物，并吸收水解产物作为营养。我们研究了一个包含双组分系统DegS-DegU的信号转导系统，该系统调节胞外降解酶的产生。用于研究细胞过程 ...更多信息 一般来说，最有用的办法是利用遗传手段。然而，对于DegS-DegU系统，已经应用了许多遗传方法，因此获得新发现的可能性似乎很低。因此，我们试图找到可能影响DegS-DegU信号转导的化学试剂。结果，发现已知通过影响核糖体功能来抑制蛋白质生物合成的抗生素如林可霉素和红霉素可阻止碱性蛋白酶基因aprE（DegS-DegU系统的靶标）的表达。在这项研究中，我们试图确定抗生素的靶标，通过该靶标DegS-DegU传递信号以诱导aprE的表达。我们发现林可霉素抑制RelA依赖性ppGpp合成。此外，aprE的表达在relA缺陷的细胞中大大降低。这些结果表明，林可霉素通过抑制ppGpp合成来阻止aprE表达。这是第一次有抗生素抑制信号转导的报道。我们还将微阵列分析应用于B。枯草双组分系统，携带一个螺旋-转角-螺旋基序的调节器，并发现网络之间形成的几个系统。少

Microorganisms in nature show various modes of life style. Bacillus subtilis is a soil bacterium that encounters severe environmental stresses such as nutritional deficiency, desiccation, drastic temperature changes and so on. The bacterium, however, carries various means to cope with these unfavorable situations. Against nutritional deficiency, for example, it secretes proteases and degradative enzymes to digest high molecular weight proteins or carbohydrates that happen to be present around the cell, and takes up the hydrolyzed products for nutrition. The machinery that serves to sense the environment is thought to be the two-component regulatory system in which the sensor kinase detect environmental cues and phosphorylates the cognate regulator, which then activates the target genes.We have studied a signal transduction system involving a two-component system, DegS-DegU, which regulates the production of extracellular degradative enzymes. For the investigation of cellular processes … More in general, the most useful approach will be to use genetic means. For the DegS-DegU system, however, many genetic approaches have already been applied, and therefore the possibility to obtain new findings seemed to be low. We tried, therefore, to find chemical agents that might affect the signal transduction involving DegS-DegU. As a result, antibiotics such as lincomycin and erythromycin that are known to inhibit protein biosynthesis through affecting the ribosomal function were found to prevent the expression of the alkaline protease gene, aprE, the target of the DegS-DegU system. In this study we tried to identify the target of the antibiotics through which the DegS-DegU transmits a signal to induce the expression of aprE. We found that lincomycin inhibits RelA-dependent ppGpp synthesis. Furthermore, the expression of aprE was greatly reduced in relA-deficient cell. These results indicate that lincomycin prevents aprE expression by inhibiting ppGpp synthesis. This is the first report that an antibiotic inhibits signal transduction.We also applied microarray analysis on B. subtilis two-component systems that carry a helix-tum-helix motif in the regulator, and found that networks are formed among several of the systems. Less