mRNA Degradation Rates Are Coupled to Metabolic Status in Mycobacterium smegmatis
mRNA Degradation Rates Are Coupled to Metabolic Status in Mycobacterium smegmatis
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DOI：
10.1128/mbio.00957-19
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发表时间：
2019-07
期刊：
影响因子：
6.4
通讯作者：
Diego A. Vargas-Blanco;Ying Zhou;L. G. Zamalloa;T. Antonelli;Scarlet S. Shell
中科院分区：
文献类型：
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作者：
Diego A. Vargas-Blanco;Ying Zhou;L. G. Zamalloa;T. Antonelli;Scarlet S. Shell
结核病治疗的后勤工作很困难，需要多种药物长达数月。结核分枝杆菌的存活部分是通过进入非生长状态，在这种状态下，它的代谢活性较低，因此对抗生素较不敏感。基本知识如何M。结核病在这些低代谢状态下存活的可能性是不完全的，我们假设优化的能量资源管理是重要的。在这里，我们报告说，减缓mRNA周转是一个共同的特点，分枝杆菌在能源压力下，但并不依赖于一般已在文献中假设的机制。最后，我们发现mRNA稳定性和生长状态可以通过导致生长停滞但增加代谢活性的药物解耦，这表明mRNA稳定性响应于代谢状态而不是生长速率本身。我们的研究结果表明，需要重新定位全球mRNA稳定性的研究，以确定可能负责的新机制。结核分枝杆菌作为人类病原体的成功部分是由于其通过进入非生长状态而在应激条件下存活的能力，例如缺氧或营养缺乏。在这些低代谢状态下，M.结核病可以耐受抗生素，并产生基因编码的抗生素耐药性，使其对压力的代谢适应对生存至关重要。大量的细菌，包括M.结核病，已经显示在生长限制和应激下降低它们的mRNA降解速率。虽然这种反应的存在似乎在物种间是保守的，但潜在的细菌mRNA稳定机制仍然未知。为了更好地了解非生长分枝杆菌的生物学，我们试图确定在非致病性模型耻垢分枝杆菌中mRNA稳定的机制基础。我们发现，mRNA的半衰期是响应于能量应激，与碳饥饿和缺氧引起的全球mRNA的稳定。当缺氧适应的培养物重新暴露于氧气时，即使在没有新转录的情况下，这种全局稳定性也会迅速逆转。严格的反应和RNase水平不能解释mRNA的稳定，也没有转录丰度。这使我们假设生长停止期间的代谢变化影响降解蛋白的活性，增加mRNA的稳定性。事实上，贝达喹啉和异烟肼这两种对细胞能量状态有相反作用的药物，对生长停滞细胞中的mRNA半衰期有相反的作用。总之，我们的研究结果表明，分枝杆菌中的mRNA稳定性不直接受生长状态的调节，而是依赖于能量代谢的状态。结核病治疗的后勤工作很困难，需要多种药物治疗数月。结核分枝杆菌的存活部分是通过进入非生长状态，在这种状态下，它的代谢活性较低，因此对抗生素较不敏感。基本知识如何M。结核病在这些低代谢状态下存活的可能性是不完全的，我们假设优化的能量资源管理是重要的。在这里，我们报告说，减缓mRNA周转是一个共同的特点，分枝杆菌在能源压力下，但并不依赖于一般已在文献中假设的机制。最后，我们发现mRNA稳定性和生长状态可以通过导致生长停滞但增加代谢活性的药物解耦，这表明mRNA稳定性响应于代谢状态而不是生长速率本身。我们的研究结果表明，需要重新定位全球mRNA稳定性的研究，以确定可能负责的新机制。
The logistics of tuberculosis therapy are difficult, requiring multiple drugs for many months. Mycobacterium tuberculosis survives in part by entering nongrowing states in which it is metabolically less active and thus less susceptible to antibiotics. Basic knowledge on how M. tuberculosis survives during these low-metabolism states is incomplete, and we hypothesize that optimized energy resource management is important. Here, we report that slowed mRNA turnover is a common feature of mycobacteria under energy stress but is not dependent on the mechanisms that have generally been postulated in the literature. Finally, we found that mRNA stability and growth status can be decoupled by a drug that causes growth arrest but increases metabolic activity, indicating that mRNA stability responds to metabolic status rather than to growth rate per se. Our findings suggest a need to reorient studies of global mRNA stabilization to identify novel mechanisms that are presumably responsible. ABSTRACT The success of Mycobacterium tuberculosis as a human pathogen is due in part to its ability to survive stress conditions, such as hypoxia or nutrient deprivation, by entering nongrowing states. In these low-metabolism states, M. tuberculosis can tolerate antibiotics and develop genetically encoded antibiotic resistance, making its metabolic adaptation to stress crucial for survival. Numerous bacteria, including M. tuberculosis, have been shown to reduce their rates of mRNA degradation under growth limitation and stress. While the existence of this response appears to be conserved across species, the underlying bacterial mRNA stabilization mechanisms remain unknown. To better understand the biology of nongrowing mycobacteria, we sought to identify the mechanistic basis of mRNA stabilization in the nonpathogenic model Mycobacterium smegmatis. We found that mRNA half-life was responsive to energy stress, with carbon starvation and hypoxia causing global mRNA stabilization. This global stabilization was rapidly reversed when hypoxia-adapted cultures were reexposed to oxygen, even in the absence of new transcription. The stringent response and RNase levels did not explain mRNA stabilization, nor did transcript abundance. This led us to hypothesize that metabolic changes during growth cessation impact the activities of degradation proteins, increasing mRNA stability. Indeed, bedaquiline and isoniazid, two drugs with opposing effects on cellular energy status, had opposite effects on mRNA half-lives in growth-arrested cells. Taken together, our results indicate that mRNA stability in mycobacteria is not directly regulated by growth status but rather is dependent on the status of energy metabolism. IMPORTANCE The logistics of tuberculosis therapy are difficult, requiring multiple drugs for many months. Mycobacterium tuberculosis survives in part by entering nongrowing states in which it is metabolically less active and thus less susceptible to antibiotics. Basic knowledge on how M. tuberculosis survives during these low-metabolism states is incomplete, and we hypothesize that optimized energy resource management is important. Here, we report that slowed mRNA turnover is a common feature of mycobacteria under energy stress but is not dependent on the mechanisms that have generally been postulated in the literature. Finally, we found that mRNA stability and growth status can be decoupled by a drug that causes growth arrest but increases metabolic activity, indicating that mRNA stability responds to metabolic status rather than to growth rate per se. Our findings suggest a need to reorient studies of global mRNA stabilization to identify novel mechanisms that are presumably responsible.