生物
使负有责任或义务
微生物群
细菌
寄主(生物学)
利基
基因组
精氨酸脱氨酶
遗传学
比较基因组学
适应(眼睛)
微生物学
宿主适应
基因组
精氨酸
基因组学
基因
生态学
氨基酸
神经科学
作者
Jing Tian,Daniel R. Utter,Lujia Cen,Pu‐Ting Dong,Wenyuan Shi,Batbileg Bor,Man Qin,Jeffrey S. McLean,Xuesong He
标识
DOI:10.1073/pnas.2114909119
摘要
Saccharibacteria are a group of widespread and genetically diverse ultrasmall bacteria with highly reduced genomes that belong to the Candidate Phyla Radiation. Comparative genomic analyses suggest convergent evolution of key functions enabling the adaptation of environmental Saccharibacteria to mammalian microbiomes. Currently, our understanding of this environment-to-mammal niche transition within Saccharibacteria and their obligate episymbiotic association with host bacteria is limited. Here, we identified a complete arginine deiminase system (ADS), found in further genome streamlined mammal-associated Saccharibacteria but missing in their environmental counterparts, suggesting acquisition during environment-to-mammal niche transition. Using TM7x, the first cultured Saccharibacteria strain from the human oral microbiome and its host bacterium Actinomyces odontolyticus, we experimentally tested the function and impact of the ADS. We demonstrated that by catabolizing arginine and generating adenosine triphosphate, the ADS allows metabolically restrained TM7x to maintain higher viability and infectivity when disassociated from the host bacterium. Furthermore, the ADS protects TM7x and its host bacterium from acid stress, a condition frequently encountered within the human oral cavity due to bacterial metabolism of dietary carbohydrates. Intriguingly, with a restricted host range, TM7x forms obligate associations with Actinomyces spp. lacking the ADS but not those carrying the ADS, suggesting the acquired ADS may also contribute to partner selection for cooperative episymbiosis within a mammalian microbiome. These data present experimental characterization of a mutualistic interaction between TM7x and their host bacteria, and illustrate the benefits of acquiring a novel pathway in the transition of Saccharibacteria to mammalian microbiomes.
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