The Regulation of Gene Expression in Streptomyces: ROW Award

某些在孢子形成过程中受阻的变色葡萄球菌突变体的特性有力地表明，碳源分解代谢物抑制、抗生素合成基因的激活和形态发育之间存在直接联系。作为我们研究这些复杂的代谢和发育过程如何相互作用的起点，我们选择了详细描述控制S. coelicolor gal操纵子转录活性的调控机制。一种相对简单的转录单位，受葡萄糖介导的分解代谢抑制和半乳糖诱导。我们建议：1)纯化和表征转录gal的聚合酶形式，2)定义决定其调控的操纵子的顺式作用元件，以及3)鉴定和分离介导抑制和诱导的反式作用因子。链霉菌属细菌的成员具有巨大的工业重要性，因为它们是大约80%已知抗生素的来源。由于其生命周期的复杂性，从遗传和发育的角度来看，这些物种也引起了极大的兴趣。当营养被剥夺时，这些细菌经历复杂的形态分化，最终产生休眠孢子，这些孢子可以在环境条件有利于营养生长的时间和地点发芽。抗生素的合成与这一发育过程密切相关，因为它发生在发育过程中，因为许多发育受阻的突变体不能产生抗生素。很明显，发育开始的信号之一是易于吸收的碳源（如葡萄糖）的消耗。这个信号被转化为开始发育过程的决定的机制目前还不清楚，但一个可行的假设是，这个机制与在葡萄糖生长过程中，那些在这些条件下不重要的基因活性被关闭的机制有关。这种类型的关闭机制尚未在链霉菌中进行详细研究，但已经清楚的是，它与其他不相关的细菌物种的类似但更好理解的机制有很大不同。这一阐明对葡萄糖生长不必要的基因关闭机制的建议特别有趣，因为这一过程在这种细菌的复杂生命周期中具有中心重要性（它也恰好是一种具有重要工业意义的物种），并且普遍感兴趣，因为它可能建立新的基因活性控制原则。

The properties of certain S. coelicolor mutants blocked in the initiation of sporulation strongly suggest a direct connection between carbon-source catabolite repression, activation of antibiotic synthesis genes and morphological development. As a starting point for our investigation of how these complex metabolic and developmental processes interact, we have chosen to characterize in detail the regulatory mechanisms that control the transcriptional activity of the gal operon of S. coelicolor, a relatively simple transcription unit that is subject to both glucose-mediated catabolite repression and induction by galactose. It is proposed to: 1) purify and characterize the polymerase forms that transcribe gal, 2) define the cis-acting elements of the operon that determine its regulation, and 3) identify and isolate the trans-acting factors that mediate repression and induction. Members of the bacterial genus Streptomyces are of enormous industrial importance, since they are the source of about 80% of known antibiotics. These species are also of great interest from a genetic and developmental point of view because of the complexity of their life cycle. When deprived of nutrients, these bacteria undergo a complex morphological differentiation culminating in the production of dormant spores which can germinate when and where environmental conditions favor vegetative growth. The synthesis of antibiotics is intimately related to this developmental process, since it occurs during the development, and since many mutants blocked in development can't make antibiotics. It is clear that one of the signals for initiation of development is depletion of an easily assimilable carbon source, such as glucose. The mechanism whereby this signal is translated into a decision to begin the developmental process is not at all understood, but a working hypothesis is that this mechanism is related to one by which, during growth on glucose, genes whose activity is not essential under these conditions are shut off. The mechanism of this type of shutoff has yet to be investigated in detail in Streptomyces, but it is already clear that it is very different from analogous but much better understood mechanisms in other unrelated species of bacteria. This proposal to elucidate the mechanism of shutoff of a gene unnecessary for growth on glucose is of particular interest because of the central importance of this process in the complex life cycle of this bacterium (which also happens to be a species of great industrial importance), and is of general interest because it may establish new principles of control of gene activity.