Awakening of a Dormant Cyanobacterium from Nitrogen Chlorosis Reveals a Genetically Determined Program
Awakening of a Dormant Cyanobacterium from Nitrogen Chlorosis Reveals a Genetically Determined Program
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DOI：
10.1016/j.cub.2016.08.054
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发表时间：
2016-11-07
期刊：
影响因子：
9.2
通讯作者：
Forchhammer, Karl
中科院分区：
文献类型：
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作者：
Klotz, Alexander;Georg, Jens;Forchhammer, Karl
微生物细胞从静止状态到活跃的植物状态的转变所涉及的分子和生理机制对于解决从微生物生态学到感染微生物学的领域中的问题至关重要。不能固氮的蓝藻能够在长时间的氮饥饿中存活，因为褪绿细胞处于休眠状态。当提供可用的氮源时，这些细胞在48小时内重新变绿并恢复营养生长。在这里，我们在生理和分子水平上研究了褪绿集胞藻PCC 6803细胞的复苏，旨在了解休眠细菌的觉醒过程。在加入硝酸盐后，细胞几乎立即启动了一个高度组织化的复苏程序。在第一阶段，它们抑制任何残余的光合作用活性，并激活呼吸以从糖原分解中获得能量。同时，他们恢复了整个翻译装置，ATP合成和硝酸盐同化。仅12-16小时后，细胞重新激活光合机构的合成，并准备进行光合作用的代谢重新布线。48小时后，当细胞达到完全光合能力时，它们恢复细胞分裂并进入营养细胞周期。对复苏过程中转录动力学的分析揭示了与观察到的生理过程的完美匹配，并表明非编码RNA在唤醒细胞的生活方式转换过程中起着主要的调节作用。这种基因编码的程序确保了栖息地的快速殖民化，其中氮饥饿施加了反复出现的生长限制。
The molecular and physiological mechanisms involved in the transition of microbial cells from a resting state to the active vegetative state are critically relevant for solving problems in fields ranging from microbial ecology to infection microbiology. Cyanobacteria that cannot fix nitrogen are able to survive prolonged periods of nitrogen starvation as chlorotic cells in a dormant state. When provided with a usable nitrogen source, these cells re-green within 48 hr and return to vegetative growth. Here we investigated the resuscitation of chlorotic Synechocystis sp. PCC 6803 cells at the physiological and molecular levels with the aim of understanding the awakening process of a dormant bacterium. Almost immediately upon nitrate addition, the cells initiated a highly organized resuscitation program. In the first phase, they suppressed any residual photosynthetic activity and activated respiration to gain energy from glycogen catabolism. Concomitantly, they restored the entire translational apparatus, ATP synthesis, and nitrate assimilation. After only 12-16 hr, the cells re-activated the synthesis of the photosynthetic apparatus and prepared for metabolic re-wiring toward photosynthesis. When the cells reached full photosynthetic capacity after 48 hr, they resumed cell division and entered the vegetative cell cycle. An analysis of the transcriptional dynamics during the resuscitation process revealed a perfect match to the observed physiological processes, and it suggested that non-coding RNAs play a major regulatory role during the lifestyle switch in awakening cells. This genetically encoded program ensures rapid colonization of habitats in which nitrogen starvation imposes a recurring growth limitation.