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首页> 外文学位 >Components of the Ubiquitin/26S proteasome system regulate abscisic acid signaling and development in Arabidopsis thaliana.
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Components of the Ubiquitin/26S proteasome system regulate abscisic acid signaling and development in Arabidopsis thaliana.

机译：泛素/ 26S蛋白酶体系统的组件调节拟南芥中的脱落酸信号传导和发育。

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摘要

Protein turnover by the Ubiquitin (Ub)/26S proteasome System (UPS) is an important proteolytic pathway that selectively removes misfolded/abnormal and short-lived regulatory proteins in eukaryotes. Commitment to breakdown begins with the attachment of a Ub polymer onto a target protein in an ATP-dependent enzyme cascade. The poly-Ub chain marks the protein for degradation by the 26S proteasome, which cleaves the target into protein fragments, with the concomitant release of reusable Ub moieties by de-ubiquitinating enzymes (DUBs). The 26S proteasome is a multi-subunit, self-compartmentalized protease in the nucleus and cytoplasm that controls the turnover of numerous cellular constituents. The subunit RPN10 is a Ub receptor in the complex that identifies a subset of targets, including the abscisic acid (ABA) signaling transcription factor ABA-INSENSITIVE-5 (ABI5). ABI5 transcriptionally activates downstream genes that induce post-germinative growth arrest in response to adverse environmental conditions. The selective turnover of ABI5 is essential for seedlings to reestablish growth when suboptimal conditions are alleviated. To further characterize ABI5 breakdown by the UPS, I identified the RING Ub ligase KEEP ON GOING (KEG) as an effector of ABI5 degradation in Arabidopsis thaliana. When KEG expression was eliminated, ABI5 protein hyperaccumulated without sensing ABA, causing a severe growth arrest of seedlings. I found that phosphorylated forms of ABI5 were present in tissues of arrested seedlings, and I demonstrated that the known ABA-responsive SNF1-RELATED PROTEIN KINASE-2.2 (SnRK2.2) and SnRK2.3 coordinately promoted ABI5 phosphorylation. SnRK2.2/2.3 elimination partially rescued keg growth arrest, altered ABI5 phosphorylation, and inhibited ABI5 accumulation.;In yeast, targets are shuttled to the 26S proteasome by soluble Ub receptors such as the Ub-like (UBL)/Ub-associated (UBA) protein RADIATION SENSITIVE-23 (RAD23), which interacts with RPN10. I identified four conserved RAD23(a-d) orthologs in Arabidopsis that bind Ub-conjugates and associate with 26S proteasomes in vivo. Reverse genetic analyses revealed that RAD23b mutations generate growth defects throughout development, while a loss of all RAD23 expression results in embryonic lethality. Additionally, rad23 mutants are sensitive to mitomycin C, which cross-links DNA and inhibits mitosis, indicating a potential role for plant RAD23 proteins in DNA repair. This work provides the first detailed description of RAD23 function in plants.
机译：泛素（Ub）/ 26S蛋白酶体系统（UPS）的蛋白质更新是重要的蛋白水解途径，可选择性去除真核生物中错误折叠/异常和短寿命的调节蛋白。对分解的承诺始于将Ub聚合物附着到ATP依赖性酶级联反应中的目标蛋白质上。聚-Ub链标记了蛋白质被26S蛋白酶体降解的过程，该酶将靶标切割成蛋白质片段，并伴随着去泛素化酶（DUB）释放可重复使用的Ub部分。 26S蛋白酶体是细胞核和细胞质中的一个多亚基，自我分隔的蛋白酶，可控制许多细胞成分的更新。 RPN10亚基是复合物中的Ub受体，可识别靶标的一个子集，包括脱落酸（ABA）信号转录因子ABA-INSENSITIVE-5（ABI5）。 ABI5转录激活下游基因，以响应不利的环境条件诱导萌发后的生长停滞。当亚最佳条件缓解时，ABI5的选择性更新对于幼苗重新生长至关重要。为了进一步描述UPS对ABI5的破坏，我确定了RING Ub连接酶KEEP ON GOING（KEG）是拟南芥中ABI5降解的效应子。当消除KEG表达时，ABI5蛋白过度积累而没有感觉到ABA，导致幼苗的严重生长停滞。我发现被捕苗的组织中存在ABI5的磷酸化形式，我证明了已知的ABA响应SNF1相关蛋白激酶2.2（SnRK2.2）和SnRK2.3协同促进了ABI5磷酸化。 SnRK2.2 / 2.3的消除部分挽救了小桶的生长停滞，改变了ABI5的磷酸化并抑制了ABI5的积累。在酵母中，靶标通过可溶性Ub受体（如Ub样（UBL）/ Ub相关的（ UBA）蛋白RADIATION SENSITIVE-23（RAD23），与RPN10相互作用。我在拟南芥中鉴定了四个保守的RAD23（a-d）直系同源物，它们在体内与Ub结合物结合并与26S蛋白酶体结合。反向遗传分析表明，RAD23b突变在整个发育过程中都会产生生长缺陷，而所有RAD23表达的丧失都会导致胚胎致死。此外，rad23突变体对丝裂霉素C敏感，丝裂霉素C交联DNA并抑制有丝分裂，表明植物RAD23蛋白在DNA修复中具有潜在作用。这项工作提供了植物中RAD23功能的第一个详细描述。

著录项

  • 作者

    Farmer, Lisa Marie.;

  • 作者单位

    The University of Wisconsin - Madison.;

  • 授予单位 The University of Wisconsin - Madison.;
  • 学科 Biology Genetics.;Biology Plant Physiology.
  • 学位 Ph.D.
  • 年度 2009
  • 页码 274 p.
  • 总页数 274
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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