ISOLATION OF EARLY SPORULATION GENES

枯草芽孢杆菌的孢子形成，原核细胞的一个例子 分化，只有当细胞被限制为必需的， 营养素 此类条件导致SpoOA的激活（磷酸化）， 一种主要的调节蛋白，负责负和正 在稳定期表达的许多基因的调节。 其中一些 基因是孢子形成所必需的，但其他基因不是;这些基因 一般参与适应营养限制，即， 这些过程是孢子形成的替代过程。 基本问题 关于孢子形成的最早阶段仍有待解答。 这些 包括引发营养或代谢信号的性质 SpoOA的磷酸化和控制早期诱导的基因表达， 固定相，这些信号影响的分子途径 SpoOA磷酸化，以及细胞将自身 在营养不良的环境中， 环境 该提案旨在确定最初的代谢信号 基于正在进行的工作，表明克雷布斯循环的酶必须 为了使这个信号有效。 的说法 克雷布斯循环酶产生一个积极的信号化合物或消除 负信号化合物将被测试，因为将克雷布斯循环的想法， 酶与参与SpoOA的蛋白质相互作用 磷酸化反应。 在以前的工作中，一种基因被鉴定出来，它的产物似乎干扰了 具有SpoOA-磷酸盐的合成或活性。 这可能是一种机制， 推迟孢子形成的承诺，直到细胞有机会 尝试适应缓慢的生长条件。 该提案旨在测试 这种蛋白质（GsiAA）抑制了 磷酸化SpoOA，并试图确定对SpoOA敏感的特定步骤。 这种抑制。 许多受SpoOA-磷酸调控的基因也受一种 第二种机制是对营养状况作出反应。 一个例子是 操纵子（DPP）负责二肽的转运。 的突变 解除DPP的营养抑制已经被孤立， 表征了 DPP的直接阻遏物将通过遗传学方法鉴定 和生化实验，并将在民进党对其活动进行测试， 启动子和其它受营养调节的启动子。 的 控制阻遏物活性的代谢物也将被 寻求。

Spore formation by Bacillus subtilis, an example of prokaryotic cellular differentiation, only occurs when cells are limited for essential nutrients. Such conditions lead to activation (phosphorylation) of SpoOA, a master regulatory protein responsible for negative and positive regulation of many genes expressed during stationary phase. Some of these genes are required for sporulation, but others are not; these latter genes are generally involved in adaptation to nutrient limitation, that is, in processes that are alternatives to spore formation. Fundamental questions about the earliest stages of sporulation remain to be answered. These include the nature of the nutritional or metabolic signals that initiate phosphorylation of SpoOA and control expression of genes induced early in stationary phase, the molecular pathway by which these signals influence SpoOA phosphorylation, and the mechanism by which the cell commits itself to sporulation as an alternative to slow growth in a nutritionally poor environment. This proposal seeks to identify the initial metabolic signal based on work in progress indicating that enzymes of the Krebs cycle must function in order for this signal to be effective. The notion that the Krebs cycle enzymes create a positive signal compound or eliminate a negative signal compound will be tested, as will the idea that Krebs cycle enzymes interact with proteins that participate in the SpoOA phosphorylation reactions. In previous work, a gene was identified whose product seems to interfere with synthesis or activity of SpoOA-phosphate. This may be a mechanism to delay the commitment to sporulation until cells have had a chance to attempt adaptation to slow growth conditions. This proposal seeks to test the idea that this protein (GsiAA) inhibits the pathway that phosphorylates SpoOA and seeks to identify the specific step sensitive to this inhibition. Many genes that are regulated by SpoOA-phosphate are also regulated by a second mechanism responsive to nutritional conditions. An example is the operon (dpp) responsible for transport of dipeptides. Mutations that relieve nutritional repression of dpp have been isolated and partially characterized. The direct repressor of dpp will be identified by genetic and biochemical experiments and will be tested for its activity at the dpp promoter and at other promoters subject to nutritional regulation. The metabolites that control the activity of the repressor will also be sought.