REGULATION OF METHIONINE METABOLISM IN BACILLUS SUBTILIS

描述(申请人提供)：一种新的全球监管体系 参与蛋氨酸代谢的基因的控制已在 枯草杆菌。利用这种机制的基因，被命名为S盒子家族， 在它们的mRNA前导区中包含一组复杂的保守初级 序列和结构元素，包括转录终止子， 竞争的反终结者和反终结者。遗传分析表明 在蛋氨酸的生长过程中，前导序列需要 抗终止子的稳定，从而防止形成 抗终止剂，这反过来又允许终止。致病的分子机制 甲硫氨酸水平对前导RNA结构的控制是 未知，尽管初步研究表明监管机构的约束力 要防止通读，需要使用系数。该系统被广泛应用于 多种革兰氏阳性菌中蛋氨酸相关基因的调控， 包括金黄色葡萄球菌等重要病原体，还发现 在革兰氏阴性菌中，泰氏氯杆菌和硫酸盐还原地杆菌。 枯草芽孢杆菌中有11个转录单位受此机制控制 因此，涉及的基因总数很高。 本研究的主要目的是进一步研究其分子机制。 转录终止控制，并阐明其生理作用 利用遗传和生化方法的组合，对这个系统进行研究。这个 所需的顺式作用序列元件将通过定点定向识别 诱变。蛋氨酸所需的反式作用调节因子 将确定响应，并将在体内和 在试管中。对ppGpp在体内有效通读的要求是 演示，并将检查这一要求的分子基础。 最后，功能未知的基因的生理作用似乎是 由这一机制监管的将被审查。

DESCRIPTION (provided by applicant): A novel global regulation system for control of genes involved in methionine metabolism has been uncovered in Bacillus subtilis. Genes utilizing this mechanism, designated the S box family, contain in their mRNA leader regions a complex set of conserved primary sequence and structural elements, including a transcriptional terminator, competing antiterminator, and anti-antiterminator. Genetic analyses indicate that during growth in methionine, sequences in the leader are required for stabilization of the anti-antiterminator, which prevents formation of the antiterminator, which in turn allows termination. The molecular mechanism for control of the leader RNA structure in response to methionine levels is unknown, although preliminary studies suggest that binding of a regulatory factor is required to prevent readthrough. This system is widely used for control of methionine-related genes in a variety of Gram-positive bacteria, including important pathogens such as Staphylococcus aureus, and is also found in the Gram-negative bacteria Chlorobium tepidum and Geobacter sulforreducens. Eleven transcriptional units are controlled by this mechanism in B. subtilis alone, so the total number of genes involved is high. The major goal of this study is to further investigate the molecular mechanism of transcription termination control, and to elucidate the physiological role of this system, using a combination of genetic and biochemical approaches. The required cis-acting sequence elements will be identified by site-directed mutagenesis. The trans-acting regulatory factors required for the methionine response will be identified, and the system will be examined both in vivo and in vitro. A requirement for ppGpp for efficient readthrough in vivo has been demonstrated, and the molecular basis for this requirement will be examined. Finally, the physiological role of genes of unknown function which appear to be regulated by this mechanism will be examined.