Mechanisms for Desiccation Tolerance in Cyanobacterium Nostoc commune

蓝藻发菜公社的干燥耐受性机制

• 批准号: 9513157
• 负责人: Malcolm Potts
• 金额: $ 24万
• 依托单位: Virginia Polytechnic Institute and State University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1996
• 资助国家: 美国
• 起止时间: 1996-03-01 至 1999-02-28
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9513157&HistoricalAwards=false
• 关键词: Mechanisms; Desiccation; Tolerance; Cyanobacterium; Nostoc

Potts9513157Actively growing cells are particularly sensitive to air-drying and most die instantly upon exposure to the atmosphere. In contrast, the members of a small, diverse group of prokaryotic and eukaryotic organisms have the capacity to withstand the most acute of cell-water deficits. How they do so remains an intriguing problem in biology. One cyanobacterium, Nostoc Commune, has a marked capacity for desiccation tolerance and has been developed as a model for the anhydrobiotic prokaryotic cell. In response to air-drying cells of N. commune synthesize water stress polypeptides (Wsp) that constitute around 70% of the total soluble cell protein and approximately 2% of the dry weight of a desiccated colony. Wsp remain stable in cells stored for decades in the air-dried state. Wsp are secreted and accumulate within a complex extracellular polysaccharide (EPS) that completely envelops the cell filaments. Within the EPS the Wsp form multimeric complexes, through strong ionic interactions, with a secreted, water-soluble UV-A/B-absorbing pigment (UVP).The principle objectives of this study are: 1) to isolate wsp from Nostoc, and to characterize the gene, its flanking regions and its control elements; 2) to understand how wsp transcription and Wsp synthesis are regulated by water stress; and 3) to crystallize Wsp. The secretion of EPS and UVP by N. commune represent two strategies that the cells use to achieve protection during long-term desiccation. The evidence found by Dr. Potts suggests that Wsp play a role in one or both of these strategies. The knowledge of how N. commune overcomes acute cell-water deficit will provide an insight into the underlying mechanisms of desiccation tolerance in all organisms.

活跃生长的细胞对空气干燥特别敏感，大多数暴露在大气中立即死亡。相比之下，原核生物和真核生物的一个小而多样的群体的成员有能力承受最严重的细胞缺水。它们是如何做到这一点的，仍然是生物学中一个有趣的问题。一种蓝藻，Nostoc公社，具有显著的耐干燥能力，并已发展为无水生物原核细胞的模型。在对空气干燥的反应中，N. commune的细胞合成水分胁迫多肽（water stress polypeptide, Wsp）， Wsp约占细胞可溶性蛋白总量的70%，约占干燥菌落干重的2%。Wsp在风干状态下储存几十年仍能保持稳定。Wsp分泌和积累在一个复杂的细胞外多糖（EPS），完全包裹在细胞丝。在EPS内，Wsp通过强离子相互作用，与分泌的水溶性UV-A/ b吸收色素（UVP）形成多聚配合物。本研究的主要目的是：1)从Nostoc中分离wsp，并对其基因、侧翼区及其控制元件进行鉴定；2)了解水分胁迫对wsp转录和合成的调控；3)使Wsp结晶。蚕豆分泌EPS和UVP代表了细胞在长期干燥中获得保护的两种策略。波茨博士发现的证据表明，科进在其中一种或两种策略中都发挥了作用。了解N.公社如何克服急性细胞缺水将提供对所有生物的干燥耐受性的潜在机制的见解。