Impaired glycogen synthesis causes metabolic overflow reactions and affects stress responses in the cyanobacterium Synechocystis sp PCC 6803
Impaired glycogen synthesis causes metabolic overflow reactions and affects stress responses in the cyanobacterium Synechocystis sp PCC 6803
复制标题
DOI：
10.1099/mic.0.062950-0
复制
发表时间：
2012-12-01
期刊：
影响因子：
2.8
通讯作者：
Zilliges, Yvonne
中科院分区：
文献类型：
--
作者：
Gruendel, Marianne;Scheunemann, Ramon;Zilliges, Yvonne
糖原或淀粉的生物合成是由活生物体开发的用于细胞内碳和能量储存的主要策略之一。在光养生物体中，这种聚葡聚糖由于光合作用期间的碳固定而积累，并用于在黑暗时期为细胞完整性、功能和活力提供维持能量。此外，据推测，糖原使蓝藻科普短暂的饥饿条件下，在大多数微生物中观察到的。在这里，糖原积累时，适当的碳源是足够的数量，但生长受到抑制，缺乏其他营养素。在这项研究中，糖原在光合蓝藻的能量和碳代谢的作用，首先分析了通过比较的生理和代谢特性的基因敲除突变体缺陷的糖原合成。我们首先证明了糖原作为呼吸底物在黑暗时期的作用，糖原作为储备生存饥饿时期，如氮耗尽和糖原合成的作用作为碳过剩条件的改善剂在模式生物集胞藻属PCC 6803的作用。我们提供了惊人的新的见解复杂的碳和氮代谢的非固氮蓝藻：一个表型的敏感性photomixotrophic条件和减少葡萄糖的摄取，非漂白表型的基础上受损的驯化反应氮耗尽，而且表型的能量溢出。这项研究表明，糖原代谢缺陷的分析是一个有价值的工具，代谢调控原则和信号的识别。
The biosynthesis of glycogen or starch is one of the main strategies developed by living organisms for the intracellular storage of carbon and energy. In phototrophic organisms, such polyglucans accumulate due to carbon fixation during photosynthesis and are used to provide maintenance energy for cell integrity, function and viability in dark periods. Moreover, it is assumed that glycogen enables cyanobacteria to cope with transient starvation conditions, as observed in most micro-organisms. Here, glycogen accumulates when an appropriate carbon source is available in sufficient amounts but growth is inhibited by lack of other nutrients. In this study, the role of glycogen in energy and carbon metabolism of phototrophic cyanobacteria was first analysed via a comparative physiological and metabolic characterization of knockout mutants defective in glycogen synthesis. We first proved the role of glycogen as a respiratory substrate in periods of darkness, the role of glycogen as a reserve to survive starvation periods such as nitrogen depletion and the role of glycogen synthesis as an ameliorator of carbon excess conditions in the model organism Synechocystis sp. PCC 6803. We provide striking new insights into the complex carbon and nitrogen metabolism of non-diazotrophic cyanobacteria: a phenotype of sensitivity to photomixotrophic conditions and of reduced glucose uptake, a non-bleaching phenotype based on an impaired acclimation response to nitrogen depletion and furthermore a phenotype of energy spilling. This study shows that the analysis of deficiencies in glycogen metabolism is a valuable tool for the identification of metabolic regulatory principles and signals.