BBSRC-NSF/BIO: Investigating microbial predation as a driver of endosymbiosis and phagocyte evasion

BBSRC-NSF/BIO：研究微生物捕食作为内共生和吞噬细胞逃避的驱动因素

• 批准号: 2202410
• 负责人: Jessie Uehling
• 金额: $ 59.15万
• 依托单位: Oregon State University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2022
• 资助国家: 美国
• 起止时间: 2022-04-15 至 2025-03-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2202410&HistoricalAwards=false
• 关键词: BBSRC; NSF; BIO; Investigating; microbial

Soil microbes compete. As a result they evolved tools to resist their enemies. However, there is also evidence of collaboration between microbes (endosymbiosis), where bacteria live inside fungal cells. We have shown that, together, a bacterial endosymbiont and its fungal host create a holobiont that can make a powerful toxin that blocks soil-dwelling amoebae from engulfing the fungus. This endosymbiotic bacterium also changes how the fungus controls its own gene expression to fight different kinds of stress. This project examines how frequently fungi and endosymbionts evade amoebae; the implications for fungal housing of endosymbionts; and whether these symbioses lead to co-evolution. To answer these questions, we will look at bacterial-fungal partnerships across a wide range of species, looking for differences and commonalities in their shared genomes. We will also record reactions of wild-type and mutant fungal-bacterial endosymbionts with amoebae in the lab to identify the different strategies they can take to evade amoebae engulfment. Finally, we will examine one endosymbiont pair in depth to understand the mechanisms that allow these partnerships to exist. Amoebae are very similar to the cells in the human immune system that are the first line of defense against infection. Thus, this study can help our understanding of immunity. Additional broader impacts of this proposal include developing fungal biological education modules and teaching resources in the K-6 classrooms, develop mushroom grow kits for children, and participation in science podcasts. Identifying how environmental fungi developed traits to evade immune cells is critical to understanding the causes of opportunistic fungal infections in nature and in humans. Mucoromycota are primarily soil-associated fungi, some of which are also opportunistic mammalian pathogens. We recently identified an endosymbiosis between Betaproteobacteria Ralstonia (bacterium) and Mucoromycota Rhizopus (fungus), a symbiosis that blocks engulfment and killing of the fungus by the soil-dwelling amoeba Dictyostelium and also confers virulence in animals. Endosymbioses between Betaproteobacteria and Mucoromycota are environmentally ubiquitous. Endosymbionts are also observed in approximately half of clinical Rhizopus isolates, where phagocyte-related deficiencies are a major predictor of susceptibility. We hypothesize that interactions between bacterium-fungus holobionts and soil amoeba drive their evolutionary trajectories and opportunistic virulence in mammals. We will use phenotypic, genomic, and molecular tools to dissect the holobiont-phagocyte interaction and investigate host-pathogen interactions at two levels: 1) interactions between bacteria and their fungal hosts, and 2) the effect of endosymbionts on phagocyte evasion and opportunistic virulence. We will take both an unbiased approach to survey bacterial-fungal-amoebal interactions across the genus and a directed approach to investigate the molecular mechanisms for specific bacterial-fungal isolates alone and with amoeba. These mechanistic studies will be coupled to comparative genomics analyses to reveal how evolutionary pressures exerted by amoebae drive endosymbiosis and immune evasion. This collaborative US/UK project is supported by the US National Science Foundation and the UK Biotechnology and Biological Sciences Research Council.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.

土壤微生物相互竞争。结果，他们进化出了抵抗敌人的工具。然而，也有证据表明微生物之间存在协作（内共生），即细菌生活在真菌细胞内。我们已经证明，细菌内共生体及其真菌宿主共同创造了一种全生物体，它可以产生一种强大的毒素，阻止土壤中的阿米巴原虫吞噬真菌。这种内共生细菌还改变了真菌控制自身基因表达以对抗不同类型压力的方式。该项目研究了真菌和内共生体逃避阿米巴原虫的频率；对内共生体真菌外壳的影响；以及这些共生是否导致共同进化。为了回答这些问题，我们将研究多种物种的细菌-真菌伙伴关系，寻找它们共享基因组的差异和共性。我们还将在实验室中记录野生型和突变型真菌-细菌内共生体与阿米巴原虫的反应，以确定它们可以采取的不同策略来逃避阿米巴原虫的吞噬。最后，我们将深入研究一对内共生体，以了解允许这些伙伴关系存在的机制。变形虫与人类免疫系统中的细胞非常相似，免疫系统是抵御感染的第一道防线。因此，这项研究可以帮助我们了解免疫。该提案的其他更广泛的影响包括在 K-6 教室中开发真菌生物教育模块和教学资源、为儿童开发蘑菇种植套件以及参与科学播客。 确定环境真菌如何形成逃避免疫细胞的特征对于了解自然界和人类机会性真菌感染的原因至关重要。毛霉菌门主要是与土壤相关的真菌，其中一些也是机会性哺乳动物病原体。我们最近发现了 Betaproteobacteria Ralstonia（细菌）和 Mucoromycota Rhizopus（真菌）之间的内共生关系，这种共生关系可以阻止土壤中的变形虫网网柄菌吞噬和杀死真菌，并赋予动物毒力。 Betaproteobacteria 和 Mucoromycota 之间的内共生在环境中普遍存在。在大约一半的临床根霉分离株中也观察到内共生体，其中吞噬细胞相关的缺陷是易感性的主要预测因素。我们假设细菌-真菌全生物和土壤阿米巴原虫之间的相互作用驱动了它们的进化轨迹和哺乳动物中的机会性毒力。我们将使用表型、基因组和分子工具来剖析全生物-吞噬细胞的相互作用，并在两个层面上研究宿主-病原体的相互作用：1）细菌与其真菌宿主之间的相互作用，2）内共生体对吞噬细胞逃避和机会毒力的影响。我们将采用公正的方法来调查跨属的细菌-真菌-阿米巴相互作用，并采用定向方法来研究特定细菌-真菌分离株单独和与阿米巴一起的分子机制。这些机制研究将与比较基因组学分析相结合，以揭示阿米巴原虫施加的进化压力如何驱动内共生和免疫逃避。 这个美国/英国合作项目得到了美国国家科学基金会和英国生物技术和生物科学研究委员会的支持。该奖项反映了 NSF 的法定使命，并通过使用基金会的智力价值和更广泛的影响审查标准进行评估，被认为值得支持。

项目成果

Convergent reductive evolution and host adaptation in Mycoavidus bacterial endosymbionts of Mortierellaceae fungi

• DOI: 10.1016/j.fgb.2023.103838
• 发表时间: 2023-09-20
• 期刊: FUNGAL GENETICS AND BIOLOGY
• 影响因子: 3
• 作者: Amses，Kevin;Desiro，Alessandro;Uehling，Jessie
• 通讯作者: Uehling，Jessie