YoeB toxin is activated during thermal stress.
YoeB toxin is activated during thermal stress.
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DOI：
10.1002/mbo3.272
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发表时间：
2015-08
期刊：
影响因子：
3.4
通讯作者：
Hayes CS
中科院分区：
文献类型：
--
作者：
Janssen BD;Garza-Sánchez F;Hayes CS
II型毒素-抗毒素（TA）模块被认为通过暂时抑制蛋白质合成而介导应激反应，同时细胞重定向转录以适应环境变化。在这里，我们表明，YoeB，核糖体依赖性mRNase毒素，在大肠杆菌细胞生长在高温下被激活。YoeB激活依赖于Lon蛋白酶，表明热应激促进YefM抗毒素的降解增加。虽然YefM是有效地降解响应Lon的过度生产，我们发现，Lon抗原水平不增加热休克过程中，表明另一种机制占温度诱导的YefM蛋白水解。这些观察结果表明，YefM/YoeB功能适应温度胁迫。然而，这种响应不同于先前描述的TA功能模型。首先，在42°C下培养数小时后，YoeB mRNase活性得以维持，表明热活化不是瞬时的。此外，热激活的YoeB不会诱导生长停滞，也不会抑制整体蛋白质合成。事实上，大肠杆菌细胞在高温下增殖得更快，并在急性热休克时瞬间加速其生长速度。我们认为热激活的YoeB可能具有质量控制功能，通过核糖体拯救途径促进停滞的翻译复合物的再循环。
Type II toxin-antitoxin (TA) modules are thought to mediate stress-responses by temporarily suppressing protein synthesis while cells redirect transcription to adapt to environmental change. Here, we show that YoeB, a ribosome-dependent mRNase toxin, is activated in Escherichia coli cells grown at elevated temperatures. YoeB activation is dependent on Lon protease, suggesting that thermal stress promotes increased degradation of the YefM antitoxin. Though YefM is efficiently degraded in response to Lon overproduction, we find that Lon antigen levels do not increase during heat shock, indicating that another mechanism accounts for temperature-induced YefM proteolysis. These observations suggest that YefM/YoeB functions in adaptation to temperature stress. However, this response is distinct from previously described models of TA function. First, YoeB mRNase activity is maintained over several hours of culture at 42°C, indicating that thermal activation is not transient. Moreover, heat-activated YoeB does not induce growth arrest nor does it suppress global protein synthesis. In fact, E. coli cells proliferate more rapidly at elevated temperatures and instantaneously accelerate their growth rate in response to acute heat shock. We propose that heat-activated YoeB may serve a quality control function, facilitating the recycling of stalled translation complexes through ribosome rescue pathways.