Maintenance of plastid genome stability in plants

维持植物质体基因组的稳定性

• 批准号: RGPIN-2014-05373
• 负责人: Brisson, Normand
• 金额: $ 4.44万
• 依托单位: Université de Montréal
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2017
• 资助国家: 加拿大
• 起止时间: 2017-01-01 至 2018-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=628892
• 关键词: Maintenance; plastid; genome; stability; plants

Photosynthesis is one of the most important biological processes on earth. All our food and a large part of our needs for fibre and building materials are provided by this process, either directly or indirectly. Photosynthesis occurs in the chloroplast, and depends on a subset of genes that are located in this organelle and in the nucleus. The genes present in the chloroplast are part of the plastid genome and encode for RNA and proteins involved in photosynthesis, gene transcription and protein synthesis. Despite the crucial importance of this genome for plants and life in general, we still know very little about its transcription, replication and DNA repair mechanisms. In recent years my laboratory has characterized a small family of plant specific DNA-binding proteins, called Whirly, as well as a specialized type-I polymerase, PolIB, that are involved in the maintenance of plastid genome stability. In the next granting period we propose to continue our characterization of the mechanisms that contribute to maintain the stability of the plastid genome. We will focus our attention mostly on a few genes whose mutation leads to hypersensitivity to the organelle-specific DNA double-stranded breaks inducing agent ciprofloxacin. These genes code for the WHY1 and WHY3 proteins, the plastid Sigma factor SIG6, the recombinase RecA1, the PolIB DNA polymerase and the RecG functional homolog DRT111. We will determine the genetic interactions between these genes, which should provide important clues to understand the mechanisms that maintain plastid genome stability. As preliminary results indicate that the transcription regulator SIG6 acts as an important mediator of genome stability, we will test the hypothesis that transcription has a strong genome destabilization effect in plastids at an early stage of development and that Whirly proteins contribute to counteract this effect.

光合作用是地球上最重要的生物过程之一。我们所有的食物以及我们对纤维和建筑材料的大部分需求都是由这一过程直接或间接提供的。光合作用发生在叶绿体中，依赖于位于该细胞器和细胞核中的一组基因。叶绿体中存在的基因是叶绿体基因组的一部分，编码参与光合作用、基因转录和蛋白质合成的RNA和蛋白质。尽管该基因组对植物和一般生命至关重要，但我们仍然对其转录、复制和DNA修复机制知之甚少。近年来，我的实验室鉴定了一小类植物特有的DNA结合蛋白，称为Whirly，以及一种专门的I型聚合酶PolIB，它们参与了维持叶绿体基因组的稳定。在下一个授权期内，我们建议继续描述有助于维持叶绿体基因组稳定性的机制。我们将主要关注一些基因的突变导致对细胞器特异性DNA双链断裂诱导剂环丙沙星的超敏反应。这些基因编码WHY1和WHY3蛋白、质体Sigma因子SIG6、重组酶RecA1、PolIB DNA聚合酶和RecG功能同源基因DRT111。我们将确定这些基因之间的遗传相互作用，这将为理解维持叶绿体基因组稳定性的机制提供重要线索。由于初步结果表明转录调控因子SIG6是基因组稳定性的重要调节因子，我们将检验这样的假设，即转录在叶绿体发育早期具有强烈的基因组不稳定效应，而Whirly蛋白有助于抵消这一效应。