Resolving the ecological biodiversity of Asgard archaea and their role in the evolution of eukaryotes

解析阿斯加德古菌的生态多样性及其在真核生物进化中的作用

• 批准号: 1753661
• 负责人: Brett Baker
• 金额: $ 28.89万
• 依托单位: University of Texas at Austin
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2018
• 资助国家: 美国
• 起止时间: 2018-02-01 至 2020-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1753661&HistoricalAwards=false
• 关键词: Resolving; ecological; biodiversity; Asgard; archaea

The processes that led to the origin of complex cellular life containing membrane-bound organelles, characteristic of all plants, animals and fungi, (i.e., eukaryotes) is still a mystery. Evidence supports the scenario where cells of different microbial lineages (archea and bacteria) merged to form the first eukaryotic cell. Recently, genomes belonging to new lineages of life, collectively called "Asgard" microorganisms, have been discovered. Surprisingly, the addition of these organisms to the tree of life have revealed a close relationship to eukaryotes, suggesting they played important roles in the origin of eukaryotes. Characterization of these genomes has detected genes previously only seen in more complex cellular life. Because currently none of the Asgard microorganism can be grown in the laboratory, this project will harness high-throughput sequencing techniques for a targeted discovery of these microorganisms from deep-sea sediments. These data will result in a more comprehensive catalog of Asgard genomes, and will be used to infer their physiological capabilities and to understand the genetic composition of their ancestor. This research will provide new insights into the biodiversity and metabolisms of Asgard microbes in deep ocean floor hydrothermal communities, and will add fundamental insights into the origin of complex eukaryotic life. This project will provide research training for undergraduate and graduate students, and will include outreach to the general public via the South Texas Science and public lectures at sciene centers in Texas. Recently, genomes (Heimdallarchaeota, Thorarchaeota, Odinarchaeota, and Lokiarchaeota phyla) belonging to the novel archaeal superphylum "Asgard" have been obtained from several anoxic environments. Surprisingly, phylogenomic analyses revealed Asgard is closely related to eukaryotes, suggesting that these organisms are descendants of the ancestral archaeal host. These Asgard phyla contain a variety of genes that encode for eukaryotic signature proteins (ESPs). ESPs are similar to eukaryotic proteins involved in a variety of processes including cytoskeletal formation, vesicular trafficking, protein translocation, and glycosylation, suggesting that archaea are the origin of some of the cellular complexity of eukaryotic cells. Because only few Asgard genomes are currently available, this project aims to do additional high-throughput sequencing and reconstruction of genomes from deep-sea sediments to obtain a more comprehensive genomic catalog of the Asgard superphylum. These additional genomes will be used to better resolve the phylogenetic relatedness of these archaea to eukaryotes. Researchers will also catalog the full repertoire of ESPs to better resolve their roles in the origin of cellular complexity. Finally, this project will resolve the physiological capabilities of these archaea and model the ancestral state of the Asgards. This will advance our understanding of the physiological capabilities of the last common ancestor of archaea and eukaryotes. Determining the modern and ancestral physiological states of these archaea will transform our understanding of the origin of eukaryotes.

导致含有膜结合细胞器的复杂细胞生命起源的过程，是所有植物，动物和真菌的特征，（即，真核生物）仍然是一个谜。证据支持不同微生物谱系（古细菌和细菌）的细胞合并形成第一个真核细胞的情况。最近，发现了属于新的生命谱系的基因组，统称为“Asgard”微生物。令人惊讶的是，将这些生物添加到生命树中揭示了与真核生物的密切关系，表明它们在真核生物的起源中发挥了重要作用。对这些基因组的表征已经发现了以前只在更复杂的细胞生命中看到的基因。由于目前没有一种Asgard微生物可以在实验室中生长，该项目将利用高通量测序技术从深海沉积物中有针对性地发现这些微生物。这些数据将产生一个更全面的Asgard基因组目录，并将用于推断他们的生理能力和了解他们祖先的遗传组成。这项研究将为深海海底热液群落中Asgard微生物的生物多样性和代谢提供新的见解，并将为复杂真核生命的起源提供基本见解。该项目将为本科生和研究生提供研究培训，并将包括通过南德克萨斯科学和德克萨斯州科学中心的公开讲座向公众推广。 最近，基因组（Heimdallarchaeota，Thorarchaeota，Odinarchaeota和Lokiarchaeota phyla）属于新的古细菌超门“Asgard”已经从几个缺氧环境中获得。令人惊讶的是，基因组分析显示Asgard与真核生物密切相关，这表明这些生物是祖先古细菌宿主的后代。这些Asgard门含有编码真核生物特征蛋白（ESP）的多种基因。ESP类似于真核生物蛋白质，参与各种过程，包括细胞骨架形成，囊泡运输，蛋白质易位和糖基化，这表明古细菌是真核细胞的一些细胞复杂性的起源。由于目前只有少数Asgard基因组可用，该项目旨在对深海沉积物的基因组进行额外的高通量测序和重建，以获得更全面的Asgard超门基因组目录。这些额外的基因组将被用来更好地解决这些古细菌的系统发育相关性真核生物。研究人员还将对ESP的全部功能进行编目，以更好地解决它们在细胞复杂性起源中的作用。最后，该项目将解决这些古菌的生理能力，并模拟阿斯加德人的祖先状态。这将促进我们对古生菌和真核生物最后共同祖先的生理能力的理解。确定这些古生菌的现代和祖先的生理状态将改变我们对真核生物起源的理解。

项目成果

Asgard archaea capable of anaerobic hydrocarbon cycling

• DOI: 10.1038/s41467-019-09364-x
• 发表时间: 2019-04
• 期刊: Nature Communications
• 影响因子: 16.6
• 作者: K. Seitz;Nina Dombrowski;Laura Eme;A. Spang;Jonathan Lombard;J. Sieber;A. Teske;Thijs J. G. Ettema;B. Baker

Proposal of the reverse flow model for the origin of the eukaryotic cell based on comparative analyses of Asgard archaeal metabolism

• DOI: 10.1038/s41564-019-0406-9
• 发表时间: 2019-04
• 期刊: Nature Microbiology
• 影响因子: 28.3
• 作者: A. Spang;Courtney W. Stairs;Nina Dombrowski;Laura Eme;Jonathan Lombard;Eva F. Caceres;C. Greening