REGULATION OF METHIONINE METABOLISM IN BACILLUS SUBTILIS

描述（由申请人提供）：一种新的全球监管体系， 已经发现了参与甲硫氨酸代谢的基因的控制， 枯草芽孢杆菌。利用这种机制的基因，被命名为S盒家族， 在它们的mRNA前导区中含有一组复杂的保守的初级 序列和结构元件，包括转录终止子， 竞争性抗终止剂和抗抗终止剂。基因分析表明 在甲硫氨酸的生长过程中，前导序列是必需的， 抗-抗终止子的稳定化，其防止 抗终止剂，这反过来又允许终止。的分子机制 响应于甲硫氨酸水平的前导RNA结构的控制是 未知，尽管初步研究表明， 必须使用该因子以防止通读。该系统广泛用于 控制多种革兰氏阳性菌中的甲硫氨酸相关基因， 包括重要的病原体，如金黄色葡萄球菌， 在革兰氏阴性菌Chlorobium tepidum和Geelobium sulforreducens中。 在B中有11个转录单位受此机制控制。枯草 所以涉及的基因总数很高。 本研究的主要目的是进一步探讨其分子机制 转录终止控制，并阐明生理作用 这个系统，使用遗传和生物化学方法的组合。的 所需的顺式作用序列元件将通过定点 诱变蛋氨酸所需的反式作用调节因子 反应将被确定，该系统将在体内和 体外对于ppGpp用于体内有效通读的要求已经被确定。 证明，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 将对这一机制进行审查。

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.