Rapid evolution of decreased host susceptibility drives a stable relationship between ultrasmall parasite TM7x and its bacterial host.
Rapid evolution of decreased host susceptibility drives a stable relationship between ultrasmall parasite TM7x and its bacterial host.
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DOI：
10.1073/pnas.1810625115
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发表时间：
2018-11-27
影响因子：
11.1
通讯作者：
He X
中科院分区：
文献类型：
--
作者：
Bor B;McLean JS;Foster KR;Cen L;To TT;Serrato-Guillen A;Dewhirst FE;Shi W;He X
不依赖于培养的测序揭示了大量的细菌物种。其中最神秘的是候选辐射门的成员，估计占所有细菌多样性的26%以上。这组超小的细菌被认为大多是共生体;然而，由于无法培养它们，对这些细菌的了解受到了阻碍。在这里，我们研究了唯一成功培养的候选Phyla Radiation菌株TM 7 x，并证明它对其细菌宿主具有毒性和致命性。然而，宿主可以迅速进化到易感性降低的状态，这导致两个物种持续存在的长期寄生关系。这些发现提供了一个罕见的一瞥到候选门辐射生物的生活方式和共生。大约四分之一的细菌多样性包括基因组减少的单一辐射，统称为候选门辐射。最近，我们共分离TM 7 x，一个超小的菌株的候选门辐射门Saccharomyces细菌，其细菌宿主溶牙放线菌菌株XH 001从人类口腔和稳定保持作为共培养物。我们目前的工作表明，在共培养物中，TM 7 x细胞通过仅感染一部分群体与宿主细胞建立长期寄生关系，这些群体保持活力，但表现出严重抑制的细胞分裂。与此相反，暴露于一个天真的A。溶齿菌分离物XH 001 n与TM 7 x细胞的结合导致大量TM 7 x细胞与每个宿主细胞结合，大量宿主细胞死亡和宿主群体崩溃。然而，进一步的传代表明，随着时间的推移，XH 001 n对TM 7 x的敏感性降低，并进入与XH 001相似的长期稳定关系。我们表明，这种降低的易感性是由快速的宿主进化驱动的，与许多形式的噬菌体抗性相反，它只提供部分保护。结果是一个僵局，感染的主机不能摆脱他们的寄生虫;然而，寄生虫负荷足够低，主机人口持续存在。最后，我们表明，TM 7 x可以感染，并形成稳定的长期关系，与其他物种在一个单一的分支的放线菌，显示一个狭窄的主机范围。这个系统作为一个模型，以了解如何减少基因组的寄生细菌，如候选门辐射坚持与他们的主机，并最终扩大其多样性。
Cultivation-independent sequencing has revealed enormous numbers of bacterial species. Amongst the most enigmatic are members of the Candidate Phyla Radiation, which are estimated to represent over 26% of all bacterial diversity. This group of ultrasmall bacteria are thought to be mostly symbionts; however, understanding these bacteria is hampered by an inability to culture them. Here, we study TM7x, the only strain of the Candidate Phyla Radiation successfully cultured, and demonstrate that it can be virulent and lethal for its bacterial host. The host, however, can rapidly evolve to a state of reduced susceptibility, which results in a long-term parasitic relationship in which both species persist. These findings provide a rare glimpse into the lifestyle and symbiosis of Candidate Phyla Radiation organisms. Around one-quarter of bacterial diversity comprises a single radiation with reduced genomes, known collectively as the Candidate Phyla Radiation. Recently, we coisolated TM7x, an ultrasmall strain of the Candidate Phyla Radiation phylum Saccharibacteria, with its bacterial host Actinomyces odontolyticus strain XH001 from human oral cavity and stably maintained as a coculture. Our current work demonstrates that within the coculture, TM7x cells establish a long-term parasitic association with host cells by infecting only a subset of the population, which stay viable yet exhibit severely inhibited cell division. In contrast, exposure of a naïve A. odontolyticus isolate, XH001n, to TM7x cells leads to high numbers of TM7x cells binding to each host cell, massive host cell death, and a host population crash. However, further passaging reveals that XH001n becomes less susceptible to TM7x over time and enters a long-term stable relationship similar to that of XH001. We show that this reduced susceptibility is driven by rapid host evolution that, in contrast to many forms of phage resistance, offers only partial protection. The result is a stalemate where infected hosts cannot shed their parasites; nevertheless, parasite load is sufficiently low that the host population persists. Finally, we show that TM7x can infect and form stable long-term relationships with other species in a single clade of Actinomyces, displaying a narrow host range. This system serves as a model to understand how parasitic bacteria with reduced genomes such as those of the Candidate Phyla Radiation have persisted with their hosts and ultimately expanded in their diversity.
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影响因子：
11
作者：
Duran-Pinedo, Ana E.;Chen, Tsute;Frias-Lopez, Jorge
通讯作者：
Frias-Lopez, Jorge
影响因子：
3.6
作者：
Bor B;Poweleit N;Bois JS;Cen L;Bedree JK;Zhou ZH;Gunsalus RP;Lux R;McLean JS;He X;Shi W
通讯作者：
Shi W
影响因子：
3.4
作者：
Gong, Jun;Qing, Yao;Warren, Alan
通讯作者：
Warren, Alan
影响因子：
5.1
作者：
Davidov, Yaacov;Huchon, Dorothee;Jurkevitch, Edouard
通讯作者：
Jurkevitch, Edouard
DOI：
10.1128/genomea.01685-15
发表时间：
2016-02-04
期刊：
Genome announcements
影响因子：
--
作者：
McLean JS;Liu Q;Bor B;Bedree JK;Cen L;Watling M;To TT;Bumgarner RE;He X;Shi W
通讯作者：
Shi W