The effects of holoparasitism on plant organellar translation and tRNA metabolism

全寄生对植物细胞器翻译和 tRNA 代谢的影响

• 批准号: 2322154
• 负责人: Daniel Sloan
• 金额: $ 80万
• 依托单位: Colorado State University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-09-01 至 2026-08-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2322154&HistoricalAwards=false
• 关键词: effects; holoparasitism; plant; organellar; translation

The mitochondria and chloroplasts found in eukaryotes are derived from bacteria and retain their own genomes and their own molecular machinery for protein translation. This translation machinery is more conserved and bacterial-like in plants than in other eukaryotes. To test the hypothesis that the intense demands for protein production associated with photosynthesis are responsible for the natural selection that conserves plant mitochondrial and chloroplast translation machinery, this project will investigate the evolution of holoparasitic plants. These organisms have entirely lost the ability to photosynthesize and instead acquire energy by tapping into the vasculature of a host plant or consuming soil fungi. Many genes have been lost from the organellar genomes of these plants, and this research will help understand how bacterial-like enzymes can be functionally replaced by their eukaryotic counterparts even after billions of years of evolutionary divergence. In addition, it will provide insights into how the very last remaining genes in mitochondrial and chloroplast genomes can be lost and thereby complete the final steps of integrating these organelles into the eukaryotic cell. The project will also provide training for researchers at undergraduate, graduate, and postdoctoral levels in bioinformatics, molecular genetics, biochemistry, and evolutionary biology. It will also be coupled with international collaborations, outreach workshops, and a program for first-year undergraduates to broaden access to career opportunities in computational biology.Initial observations indicate that numerous components of the mitochondrial and chloroplast translation machinery in holoparasites have been lost and functionally replaced with corresponding machinery from the cytosol that is typically responsible for translating proteins encoded by nuclear genes. The perturbations to organellar translation machinery resulting from loss of photosynthesis appear to be associated with extensive rewiring of interactions between tRNAs and aminoacyl-tRNA synthetases (aaRSs). These changes will be assessed through a combination of comparative genomics, subcellular localization analysis (fluorescence microscopy), specialized tRNA sequencing methods, and in vitro aminoacylation assays. These analyses will determine the extent to which changes in subcellular targeting and aaRS substrate specificity facilitate the process of gene loss and functional replacement. They will also determine how the well-characterized parallel roles of chloroplast tRNA-Glu in both translation and tetrapyrrole biosynthesis can both be functionally replaced, leading to the loss of this gene and eventually to the loss of the entire chloroplast genome.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

真核生物中发现的线粒体和叶绿体来自细菌，它们保留着自己的基因组和自己的蛋白质翻译分子机制。这种翻译机制在植物中比在其他真核生物中更保守，更像细菌。为了验证这样一个假设，即与光合作用相关的对蛋白质生产的强烈需求是保护植物线粒体和叶绿体翻译机制的自然选择的原因，该项目将调查海生植物的进化。这些生物已经完全失去了光合作用的能力，取而代之的是通过利用寄主植物的维管系统或消耗土壤真菌来获得能量。这些植物的细胞器基因组中已经丢失了许多基因，这项研究将有助于理解即使在数十亿年的进化分歧之后，类细菌酶如何在功能上被真核生物所取代。此外，它还将提供关于线粒体和叶绿体基因组中最后残留的基因如何丢失的见解，从而完成将这些细胞器整合到真核细胞中的最后步骤。该项目还将为本科生、研究生和博士后水平的研究人员提供生物信息学、分子遗传学、生物化学和进化生物学方面的培训。它还将与国际合作、外展研讨会和一项针对一年级本科生的计划相结合，以拓宽在计算生物学领域的职业机会。初步观察表明，完整寄生虫中线粒体和叶绿体翻译机制的许多组件已经丢失，并在功能上被来自细胞质的相应机制所取代，细胞质通常负责翻译核基因编码的蛋白质。光合作用丧失对细胞器翻译机制的干扰似乎与tRNAs和氨基酰tRNA合成酶(AARs)之间的相互作用的广泛重新连接有关。这些变化将通过比较基因组学、亚细胞定位分析(荧光显微镜)、专门的tRNA测序方法和体外氨基酰化分析相结合的方法进行评估。这些分析将确定亚细胞靶向性和AARS底物专一性的变化在多大程度上促进了基因丢失和功能替换的过程。他们还将确定如何从功能上取代叶绿体tRNA-Glu在翻译和四吡咯生物合成中的并行作用，从而导致该基因的丢失，并最终导致整个叶绿体基因组的丢失。这一奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。