Presence of toxin-antitoxin systems in picocyanobacteria and their ecological implications
Presence of toxin-antitoxin systems in picocyanobacteria and their ecological implications
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DOI：
10.1038/s41396-020-00746-4
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发表时间：
2020-08-19
期刊：
影响因子：
11
通讯作者：
Chen, Feng
中科院分区：
文献类型：
--
作者：
Fucich, Daniel;Chen, Feng
微囊藻(主要是聚球藻和原氯球菌属)对海洋初级生产量有很大贡献。细菌和古细菌中存在的毒素-抗毒素(TA)系统被认为是调节细胞生长以响应环境压力的系统。然而，对苦味蓝杆菌中TA系统的存在知之甚少。本研究调查了聚球藻和原氯球藻的全基因组，了解TA系统在微囊藻中的流行情况。使用TAfinder软件，在33株聚球藻中有27株(81%)预测到了II型TA系统，但38株原氯球菌中没有一株含有TA基因，基因组越大的聚球藻倾向于含有更多的II型TA系统。在从不同环境中分离的聚球藻中，TA对的数量从0到42个不等。在海岸和淡水聚球藻的基因组大小和推测的TA系统的数量之间建立了线性关系。一般而言，开阔海域聚球藻不含TA系统或只有很少的TA系统，而沿海和淡水聚球藻含有更多的TA系统。第二类TA系统抑制微生物翻译，通过核糖核酸酶，使细胞在不利环境中进入“休眠”阶段。淡水和沿海聚球藻TA基因的遗传可以提供一种可恢复的持久机制，对在多变的环境中生存至关重要。
Picocyanobacteria (mainlySynechococcusandProchlorococcus) contribute significantly to ocean's primary production. Toxin-Antitoxin (TA) systems present in bacteria and archaea are known to regulate cell growth in response to environmental stresses. However, little is known about the presence of TA systems in picocyanobacteria. This study investigated complete genomes ofSynechococcusandProchlorococcusto understand the prevalence of TA systems in picocyanobacteria. Using the TAfinder software, Type II TA systems were predicted in 27 of 33 (81%)Synechococcusstrains, but none of 38Prochlorococcusstrains contain TA genes.Synechococcusstrains with larger genomes tend to contain more putative type II TA systems. The number of TA pairs varies from 0 to 42 inSynechococcusstrains isolated from various environments. A linear correlation between the genome size and the number of putative TA systems in both coastal and freshwaterSynechococcuswas established. In general, open oceanSynechococcuscontain no or few TA systems, while coastal and freshwaterSynechococcuscontain more TA systems. The type II TA systems inhibit microbial translationviaribonucleases and allow cells to enter the "dormant" stage in adverse environments. Inheritance of TA genes in freshwater and coastalSynechococcuscould confer a recoverable persister mechanism important to survive in variable environments.