NIGMS administrative equipment supplement for R35 GM136338-02

R35 GM136338-02 的 NIGMS 管理设备补充 资助家长奖摘要/摘要 PI：露西娅·斯特拉德 通过转录因子对基因激活或抑制进行激素介导的调节是所有疾病的核心 有机体。生长素反应因子 (ARF) 转录因子是植物生长的关键调节剂 并为探索基因激活和抑制的激素控制提供了理想的模型。 23名成员中 ARF家族中，有5个被认为是转录激活子，18个被认为是转录抑制子， 允许在一个家庭中研究这两项活动。 在低生长素浓度下，Aux/IAA 蛋白通过直接相互作用抑制 ARF 转录因子 和招募染色质重塑因子。当生长素浓度高时，辅助受体复合物 由转运抑制剂反应 1 (TIR1) 家族的 F-box 蛋白和 Aux/IAA 组成 阻遏蛋白，直接结合生长素。 F-box 蛋白参与 Skp1-Cullin-F-box (SCF) E3 泛素 连接酶，以 Aux/IAA 蛋白为目标进行降解。这种降解事件减轻了 ARF 转录 因子抑制，允许生长素调节转录。这种受体-配体相互作用允许非常短的 信号转导链促进对生长素的快速转录反应。 为了了解 ARF-ARF 和 ARF-Aux/IAA 相互作用的分子基础，我们的实验室解决了 驱动这些相互作用的结构域的结构，发现它折叠成 I/II 型 Phox 和 Bem1 (PB1) 域。在这个域内，有一个带正电和一个带负电的静电面 相反的两侧，形成两面性的蛋白质折叠。这允许从前到后的 ARF 寡聚化（类似于 一组条形磁铁）存在于堆积的晶体、溶液和植物中。 除了充分研究的抑制-去抑制调节机制之外，我们的实验室还发现 ARF 子集的活性可以通过 PB1 组合驱动的蛋白质相变进行调节 寡聚化和本质上无序的区域。这些 ARF 的相变似乎可以调节 在发育相关的背景下对生长素的反应。我们进一步发现，许多 ARF 受蛋白酶体降解调节，并鉴定出参与该过程的 E3 泛素连接酶。 最后，使用 PB1 结构域点突变可以轻松操纵 ARF 相互作用，使我们能够直接 用于研究的 ARF 相互作用。使用 ARF 作为模型将使我们能够探究转录因子的功能 易于操作的系统可以对许多转录因子产生广泛的了解。 我们的多学科方法、广泛的生长素相关分子工具包以及 我们实验室生产的独特试剂。我们实验室结合了遗传学和生物化学/生物物理学方面的专业知识 随着我们最近对 ARF 缩合和蛋白酶体降解的发现，使我们处于有利地位 推动我们对转录因子调控的相变和其他机制的理解 活动。

NIGMS administrative equipment supplement for R35 GM136338-02 Summary / Abstract of Funded Parent Award PI: Lucia Strader Hormone-mediated modulation of gene activation or repression through transcription factors is central to all organisms. AUXIN RESPONSE FACTOR (ARF) transcription factors are critical modulators of plant growth and provide an ideal model for exploring hormone control of gene activation and repression. Of the 23-member ARF family, five are considered transcriptional activators and 18 are considered transcriptional repressors, allowing for study of both of these activities in a single family. Under low auxin concentrations, Aux/IAA proteins repress ARF transcription factors via direct interaction and recruitment of chromatin remodeling factors. When auxin concentrations are high, a co-receptor complex, comprised of an F-box protein from the TRANSPORT INHIBITOR REPONSE1 (TIR1) family and an Aux/IAA repressor protein, directly binds auxin. The F-box protein participates in a Skp1-Cullin-F-box (SCF) E3 ubiquitin ligase, which targets the Aux/IAA protein for degradation. This degradation event relieves ARF transcription factor repression, allowing auxin-regulated transcription. This receptor-ligand interaction allows a very short signal transduction chain to facilitate rapid transcriptional responses to auxin. To understand the molecular underpinnings of ARF-ARF and ARF-Aux/IAA interactions, our lab solved the structure of the domain driving these interactions, finding that it folds into a Type I/II Phox and Bem1 (PB1) domain. Within this domain, there is a positively charged and a negatively charged electrostatic face on opposing sides, creating a Janus-like protein fold. This allows for front-to-back ARF oligomerization (similar to a set of bar magnets) in the packed crystal, in solution, and in the plant. In addition to the well-studied repression – derepression mechanism of regulation, our lab has discovered that activity of a subset of ARFs can be regulated by protein phase transition driven by the combination of PB1 oligomerization and an intrinsically disordered region. Phase transition of these ARFs appears to modulate responsiveness to auxin in a developmentally relevant context. We have further found that many ARFs are regulated by proteasomal degradation and have identified an E3 ubiquitin ligase involved in this process. Finally, ARF interactions can be easily manipulated using PB1 domain point mutations, allowing us to direct ARF interactions for study. Using ARFs as a model will allow us to interrogate transcription factor function in an easily manipulated system to yield broad insight into many transcription factors. We are aided in our efforts by our multidisciplinary approach, extensive auxin-related molecular toolkit, and unique reagents generated by our lab. Our lab's expertise in genetics and biochemistry/biophysics, combined with our recent discoveries of ARF condensation and proteasomal degradation, makes us well positioned to drive forward our understanding of phase transition and other mechanisms in regulation of transcription factor activity.