Metabolic mechanism and function of cyanobacterial polyphosphate in lakes

Abstract

大规模蓝藻水华暴发对湖泊水生态系统健康和饮用水安全产生巨大危害，而湖泊水体磷是影响蓝藻水华暴发程度的重要生源要素。应对水体不同磷酸盐浓度，蓝藻高效运行磷酸盐转运系统和磷酸盐特殊转运系统，并合成多聚磷酸盐（聚磷）。蓝藻胞内存在颗粒态、胶体态和可溶态3种形态的聚磷，且不同形态的聚磷分布位置不同。不同蓝藻合成聚磷颗粒的大小、数量和合成期均有所差异。多聚磷酸盐激酶、多聚磷酸盐外切酶、多聚磷酸盐内切酶和P-AMP-磷酸转移酶分别催化聚磷的合成与分解。多聚磷酸盐是二价阳离子的螯合剂，也是磷酸盐及高能磷酸键的储藏库，为细胞生存提供阳离子、磷酸盐和能量，满足蓝藻生命活动过程中生理生化活动所需，具有抵御高温、高pH、紫外线和营养盐缺乏等环境胁迫的生理功能，提升其在不利环境中的生存能力。同时，在蓝藻水华持续暴发、湖泊藻型生境稳态和磷生物地球化学循环过程中聚磷发挥重要的生态功能。因此，蓝藻合成聚磷的分子生物学机制及生态功能研究能够阐明聚磷的存在如何改变湖泊水体-沉积物磷分配、食物网中磷传递等。而开展调控聚磷合成的技术研究，通过控制蓝藻合成聚磷来减轻蓝藻水华暴发规模，将为湖泊水体良性生态系统的重构提供新方法。;Cyanobacterial blooms pose a huge harm to lake aquatic ecosystems health and drinking water safety, and the high phosphorus concentration of lake water bodies is an important inducement for the frequent outbreak of cyanobacterial blooms in lakes. The efficient operation of cyanobacterial intracellular inorganic phosphate transport system and the phosphate special transport system and polyphosphate (polyP) synthesis in cyanobacteria ensures the absorption of phosphate and its survival in phosphorus fluctuating environment. Three forms of polyP including granular, colloidal and soluble polyP, appear in cyanbacterial cells. The subcellular locations of different polyP forms are varied. The size, quantity and the growth period of polyP synthesized are different in different cyanobacterial species. The synthesis and decomposition of polyP are catalyzed by polyphosphate kinase, polyphosphate exonuclease, polyphosphate endonuclease and P-AMP-phosphate transferase, respectively. PolyP is also a chelating agent of divalent cations and a reservoir of phosphate and high-energy phosphate bonds, providing cations, phosphate and energy for cell survival. Cyanobacterial synthesizing polyP is a response to environmental stresses such as high temperature, peroxidation, and nutrient salt deficiency, which improves the viability of cyanobacteria. Therefore, the synthesis of polyP is required for physiological and biochemical activities in the life activities of cyanobacteria. In addition, the synthesis of polyP plays an important ecological function in the continuous outbreak of cyanobacterial blooms and the maintenance of the homeostasis of algal eco-environments. Therefore, it should strengthen the research on the molecular biological mechanism and the ecological function of cyanobacterial polyP synthesis. How the presence of polyphosphorus changes the phosphorus distribution in lake water-sediment and phosphorus transfer in food webs should also be elucidated. The techniques to control large-scale outbreaks of cyanobacterial blooms by controlling the synthesis of polyP in cyanobacteria may provide new methods to reconstruct benign ecosystems in lake waters.