Regulatory Specificity of the Maize Myb-Domain Proteins P and C1

9723355 Grotewold转录因子通常属于共享相关DNA结合结构域并结合相似DNA序列的蛋白质家族。 然而，这些因子能够通过激活特定的靶基因组来调节不同的细胞过程。 因此，理解具有相似DNA结合结构域的转录调节因子指导特定基因表达模式以实现生物特异性的机制是至关重要的。 本研究将探讨与Myb癌基因相关的两种玉米蛋白P和C1通过激活重叠的生物合成基因集来调节不同类黄酮色素积累的机制。 我们以前的研究表明，P和C1编码序列特异性DNA结合蛋白，识别具有不同亲和力相同的顺式作用启动子元件在一个共同调控的基因。 C1需要R/B家族的bHLH因子发挥调节功能，而P不需要，但可能需要其他尚未鉴定的细胞因子来调节缺乏高亲和力P结合位点的启动子。 如何与辅助因子的组合相互作用调节P和C1调节功能尚不清楚。 以前的研究也表明，这些蛋白质的保守的Myb结构域是足够的调节特异性：MyB结构域是唯一负责这些蛋白质的DNA结合特性，和C1的Myb结构域介导的相互作用与R/B蛋白，表明需要阐明的Myb结构域的结构，以了解如何实现生物特异性。 为了确定P和C1如何调节基因表达的特定模式，并了解植物Myb结构域蛋白如何实现生物特异性，我们将确定C1中允许它而不是P与R/B相互作用的残基。 由于C1与R/B蛋白的相互作用是C1功能的基础，我们将研究为什么C1需要R/B，而P不需要。 我们将调查是否需要额外的细胞因子的调节功能的P和C1。 这个问题很重要，因为P和C1+R/B都不足以调节缺乏这些蛋白质的高亲和力DNA结合位点的启动子。 这项研究将有助于从根本上理解转录因子调节不同基因表达以实现生物特异性的机制。 基因表达调控是所有生物体的核心过程。 转录因子通常属于共享相关DNA结合结构域并结合相似DNA序列的蛋白质家族。 然而，这些因子能够通过激活特定的靶基因组来调节不同的细胞过程。 因此，重要的是要了解具有相似的DNA结合结构域的转录调节子如何在指导特定的基因表达模式中实现生物特异性。 我们对这个生物学问题的方法是研究与Myb癌基因相关的两种玉米蛋白通过激活重叠的生物合成基因来调节不同类黄酮色素积累的机制。 这项研究将有助于从根本上了解转录因子的作用机制，调节不同基因的表达，以实现生物特异性。 ***

9723355 Grotewold Transcription factors frequently belong to families of proteins that share related DNA-binding domains and bind similar DNA sequences. Yet, these factors are able to regulate different cellular processes by activating specific sets of target genes. It is therefore fundamentally important to understand the mechanisms by which transcriptional regulators with similar DNA-binding domains direct specific patterns of gene expression to achieve biological specificity. This research will investigate the mechanisms by which P and C1, two maize proteins related to the Myb oncogene, regulate the accumulation of different flavonoid pigments by activating overlapping sets of biosynthetic genes. Our previous studies showed that P and C1 encode sequence-specific DNA-binding proteins that recognize with different affinities identical cis-acting promoter elements in a commonly regulated gene. Whereas C1 requires the bHLH factors of the R/B family for regulatory function, P does not, but may require other as yet-unidentified cellular factors to regulate promoters lacking high-affinity P-binding sites. How combinatorial interactions with accessory factors modulate P and C1 regulatory function is not known. Previous studies have also shown that the conserved Myb-domains of these proteins are sufficient for their regulatory specificity: The Myb domain is solely responsible for the DNA-binding properties of these proteins, and the Myb-domain of C1 mediates the interaction with the R/B proteins, indicating a need to elucidate the structure of Myb-domains to understand how biological specificity is achieved. To determine how P and C1 regulate specific patterns of gene expression and to understand how plant Myb-domain proteins achieve biological specificity, we will determine the residues in C1 that allow it, but not P, to interact with R/B. Since the interaction of C1 with R/B proteins is fundamental for C1 function, we will investigate why C1 requires R/B, whereas P does not. We will inv estigate whether additional cellular factors are required for the regulatory function of P and C1. This question is important because neither P nor C1+R/B are sufficient to regulate promoters lacking high-affinity DNA-binding sites for these proteins. This research will contribute to a fundamental understanding of the mechanisms used by transcription factors to regulate the expression of different genes to achieve biological specificity. %%% Regulation of gene expression is a central process in all living organisms. Transcription factors frequently belong to families of proteins that share related DNA-binding domains and bind similar DNA sequences. Yet, these factors are able to regulate different cellular processes by activating specific sets of target genes. It is therefore important to understand how transcriptional regulators with similar DNA-binding domains achieve biological specificity in directing specific patterns of gene expression. Our approach to this biological question is to investigate the mechanisms by which two maize proteins related to the Myb oncogene regulate the accumulation of different flavonoid pigments by activating overlapping sets of biosynthetic genes. This research will contribute to a fundamental understanding of the mechanisms used by transcription factors, to regulate the expression of different genes to achieve biological specificity. ***