Characterization of the Deep-Sea Streptomyces sp. SCSIO 02999 Derived VapC/VapB Toxin-Antitoxin System in Escherichia coli.
Characterization of the Deep-Sea Streptomyces sp. SCSIO 02999 Derived VapC/VapB Toxin-Antitoxin System in Escherichia coli.
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DOI：
10.3390/toxins8070195
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发表时间：
2016-07-01
期刊：
影响因子：
4.2
通讯作者：
Wang X
中科院分区：
文献类型：
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作者：
Guo Y;Yao J;Sun C;Wen Z;Wang X
毒素-抗毒素（TA）系统是原核生物中普遍存在的小分子遗传元件。大多数关于TA系统的研究都集中在海洋细菌和病原菌上，但很少有研究集中在海洋细菌中的TA，特别是那些从深海环境中分离出来的TA。在这里，我们的特点是II型VapC/VapB TA系统从深海衍生链霉菌。SCSIO 02999。VapC（毒力相关蛋白）蛋白属于PIN（PilT N-末端）超家族。过量产生VapC强烈抑制细胞生长，导致E.杆菌VapC的毒性通过直接的蛋白质-蛋白质相互作用被邻近基因编码的小蛋白抗毒素VapB中和。单独的抗毒素VapB或VapB/VapC复合物负调节vapBC启动子活性。我们进一步揭示了PIN结构域中的三个保守的Asp残基是VapC毒性作用所必需的。此外，VapC/VapB TA系统在E.杆菌此外，VapC在大肠杆菌中通过部分Lon-dependent机制交叉激活了几个TA操纵子的转录。大肠杆菌，和激活的毒素积累更优先于他们的抗毒素合作伙伴。总之，我们在深海链霉菌中鉴定和表征了一个新的深海TA系统，并证明该系统中的VapC毒素可以交叉激活E.杆菌
Toxin-antitoxin (TA) systems are small genetic elements that are ubiquitous in prokaryotes. Most studies on TA systems have focused on commensal and pathogenic bacteria; yet very few studies have focused on TAs in marine bacteria, especially those isolated from a deep sea environment. Here, we characterized a type II VapC/VapB TA system from the deep-sea derived Streptomyces sp. SCSIO 02999. The VapC (virulence-associated protein) protein belongs to the PIN (PilT N-terminal) superfamily. Overproduction of VapC strongly inhibited cell growth and resulted in a bleb-containing morphology in E. coli. The toxicity of VapC was neutralized through direct protein–protein interaction by a small protein antitoxin VapB encoded by a neighboring gene. Antitoxin VapB alone or the VapB/VapC complex negatively regulated the vapBC promoter activity. We further revealed that three conserved Asp residues in the PIN domain were essential for the toxic effect of VapC. Additionally, the VapC/VapB TA system stabilized plasmid in E. coli. Furthermore, VapC cross-activated transcription of several TA operons via a partially Lon-dependent mechanism in E. coli, and the activated toxins accumulated more preferentially than their antitoxin partners. Collectively, we identified and characterized a new deep sea TA system in the deep sea Streptomyces sp. and demonstrated that the VapC toxin in this system can cross-activate TA operons in E. coli.