RNA POLYMERASE AND BACTERIAL DIFFERENTIATION

当细菌枯草芽孢杆菌从营养体分化为 休眠的内生孢子，发生复杂的形态变化， 许多基因的表达。在这个过程中，新的RNA聚合酶σ亚基 出现，相互取代，并赋予RNA聚合酶不同的 识别不同类型启动子的特异性。的 每个sigma因子的活性似乎是响应于 形态学线索，标志着特定阶段的完成， 分化过程，在某些情况下，细胞间信号传导 前孢子和母细胞之间的连接是必需的。阐明 同步形态转化和基因表达的机制 可能导致发现新的机制， 调节多种微生物中的基因表达。所以我们 将研究同步激活两种不同的 具有两种不同形态变换的sigma因子。 SapA蛋白在孢子外壳组装的早期阶段起作用， 蛋白水解处理的同一机制，处理亲激活 从而协调sigma K的激活与 孢子衣的基础。我们将测试这个假设，并确定如何 SapA靶向于底毛和皮质之间的界面区域 肽聚糖前孢子特异性转录由sigma F-RNA启动 聚合酶，并导致前孢子特异性生产sigmaG。 然而，转录的spoIIIG，结构基因，是延迟， 相对于其他sigmaF依赖基因，需要一个未鉴定的 细胞间信号我们将描述这种细胞间的机制， 通过鉴定spoIIIG启动子中的顺式作用元件进行调控，以及 调节spoIIIG启动子活性的反式作用因子。sigmaG spoIIIG转录后积累，但不完全激活 直到完成前孢子的吞噬。我们将研究 这两种蛋白质似乎会影响sigmaG的激活。orfD的转录 编码这些蛋白质之一的基因由一个启动子引导， 任何其他已知的在孢子形成期间活跃的。因此，我们将阐明 调节orfD转录的机制。spoIIIJ基因的突变 sigmaG激活。我们将测试spoIIIJ编码一个 信息素样肽，其在信号传导sigmaG激活中起作用。

As the bacterium Bacillus subtilis differentiates from the vegetative form into a dormant endospore, complex morphological changes occur that require the expression of many genes. During the process, new RNA polymerase sigma subunits appear, displacing one another and conferring on the RNA polymerase different specificities for the recognition of different classes of promoters. The activity of each sigma factor appears to be regulated in response to morphological cues that signal the completion of specific stages in the differentiation process, and in several instances intercellular signaling between the forespore and mother cell is required. Elucidation of the mechanisms that synchronize morphological transformations and gene expression in Bacillus subtilis may lead to the discovery of novel mechanisms that regulate gene expression in a wide variety of microorganisms. Therefore, we will study the mechanisms that synchronize the activation of two different sigma factors with two different morphological transformations. SapA protein acts in the early stage of spore coat assembly and may be proteolytically processed by the same machinery that processes pro- to activate thereby coordinating the activation of sigma K with the completion of the foundation for the spore coat. We will test this hypothesis, and determine how SapA is targeted to the interface region between the undercoat and cortex peptidoglycan. Forespore-specific transcription is initiated by sigma F-RNA polymerase, and results in the forespore-specific production of sigmaG. However, transcription of spoIIIG, the structural gene for , is delayed relative to other sigmaF-dependent genes, and requires an unidentified intercellular signal. We will characterize this mechanism of intercellular regulation by identifying cis-acting elements in the spoIIIG promoter, and trans-acting factors that regulate spoIIIG promoter activity. sigmaG accumulates after transcription of spoIIIG but does not become fully active until engulfment of the forespore is completed. We will study the function of two proteins that appear to affect sigmaG activation. Transcription of the orfD gene, which encodes one of these proteins, is directed from a promoter unlike any other known to be active during sporulation. Therefore, we will elucidate the mechanism that regulates orfD transcription. Mutations in spoIIIJ prevent sigmaG activation. We will test the hypothesis that spoIIIJ encodes a pheromone-like peptide that plays a role in signaling sigmaG activation.