Combinatorial control of Met4-activated transcription

描述(申请人提供)：基因表达的调节部分是通过一种称为组合控制的保守调控机制实现的，在这种机制中，启动子上一组固定的转录因子之间的排列允许不同的转录反应。组合控制的一个方面是，结合相同启动子基序的转录因子家族如何表现不同，以实现不同的表达结果。我们在一个特性良好的酵母系统中研究了这个问题，该系统调节硫代谢基因的表达，以响应不同的环境提示。这些基因的转录依赖于一种名为Met4的激活剂。由于Met4缺乏固有的DNA结合能力，Met4依赖于与DNA结合的“辅因子”(缺乏固有激活能力的转录因子)的相互作用来靶向特定的启动子。Met4有两类DNA结合辅因子，每类结合一个不同的DNA基序。一类由基本的螺旋-环-螺旋蛋白CBF1组成；另一类由两个相似和半冗余的锌指蛋白组成：Met31和Met32。虽然我们已经发现CBF1是表达Met4靶基因子集所必需的，但当同时去除Met31和Met32后，所有Met4靶基因的表达都被消除[1]。这项建议的目的是确定Met31和Met32在介导Met4激活的转录中的单独作用。使用全基因组方法，我们将根据启动子结合和转录反应确定靶标，并计算Met31和Met32特有的DNA共识基序。我们还将研究Met31或Met32的缺失如何改变Met4转录系统中的组合成分。当将上述数据与目标启动子的组成进行比较时，我们希望对转录因子家族如何允许对其目标进行广泛的转录反应提供更详细的见解。从这项研究中发现的一般机制可能在高等真核生物中保守，这些真核生物包含更大、更复杂的转录因子家族，这些转录因子家族对这些类型的分析是困难的。 与公共健康相关：转录因子家族的成员结合相同的启动子基序，存在于真核基因调控系统中。这些家族允许对其靶标进行广泛的转录反应。通过操纵一个特性良好的酵母系统，我们将研究一个简单的两成员转录因子家族如何协调其多个靶标的基因表达，以响应不同的信号提示。

DESCRIPTION (provided by applicant): Modulation of gene expression is achieved in part by a conserved regulatory mechanism called combinatorial control, in which permutations among a fixed set of transcription factors at a promoter allow different transcriptional responses. One aspect of combinatorial control is how families of transcription factors that bind the same promoter motif behave differently to allow distinct expression outcomes. We study this issue in a well characterized yeast system that modulates expression of sulfur metabolism genes in response to varying environmental cues. Transcription of these genes depends on one activator called Met4. Since Met4 lacks intrinsic DNA binding ability, Met4 relies on interactions with DNA-binding "cofactors" (transcription factors that lack intrinsic activation ability) to target Met4 to specific promoters. There are two classes of DNA-binding cofactors for Met4 with each class binding a distinct DNA motif. One class consists of the basic helix-loop-helix protein Cbf1; the other class consists of two similar and semi-redundant zinc finger proteins: Met31 and Met32. While we have uncovered that Cbf1 is required for a subset of Met4 target genes to be expressed, all Met4 target gene expression is eliminated upon removal of both Met31 and Met32 [1]. The aim of this proposal is to determine the individual roles of Met31 and Met32 in mediating Met4-activated transcription. Using a genome-wide approach, we will identify targets in terms of promoter binding and transcriptional response and calculate DNA consensus motifs that are specific for Met31 and for Met32. We will also examine how loss of either Met31 or Met32 alters the combinatorial components within the Met4 transcriptional system. When comparing the above data with target promoter composition, we hope to provide more detailed insights into how transcription factor families allow a broad range of transcriptional responses for their targets. The general mechanisms uncovered from this study are likely to be conserved in higher eukaryotes, which contain much larger, more complex, transcription factor families that are intractable to these kinds of analyses. PUBLIC HEALTH RELEVANCE: Transcription factor families, whose members bind the same promoter motif, are found throughout eukaryotic gene regulation systems. These families allow a broad range of transcriptional responses for their targets. By manipulating a well-characterized yeast system, we will examine how a simple two-member transcription factor family orchestrates gene expression of its multiple targets in response to different signaling cues.