深渊严格嗜压菌细胞分裂过程对高静水压极端环境的适应机制研究

细菌细胞分裂是一项需要数十个蛋白协作完成的复杂生物过程。有研究称，细胞骨架蛋白FtsZ在高压条件下无法聚合形成关键的Z环结构，是阻碍压力敏感菌在高压条件下进行细胞分裂的主要原因。而深渊微生物如何能够在高压环境下实现细胞分裂，目前仍未可知。我们在前期工作中发现，不同于压力敏感菌，深渊严格嗜压菌的FtsZ蛋白具有更高的压力耐受性，可在高压条件下聚合。基于此，本项目将采用自主研发的高压原位观察及化学固定装置，通过体外和体内功能实验，鉴定严格嗜压菌FtsZ蛋白中影响其压力耐受性的关键氨基酸位点，并分析其作用机理。同时，系统分析高压对细胞分裂不同环节关键蛋白的表达和功能的影响，阐明是否存在其他因素抑制了高压条件下的细胞分裂。综合上述研究结果，探讨深渊微生物的细胞分裂过程对高静水压环境的适应机制。本研究将有助于加深对细胞分裂这一基本生命过程的认识，为揭示深渊极端生境下的生命特征做出重要贡献。

Bacterial cell division is accomplished through coordinated function of over three dozens of proteins. The Z-ring constituted mainly by cytoskeleton protein FtsZ is indispensable for this process. It has been reported that E. coli cells failed to divide under high hydrostatic pressure (HHP) conditions as a result of disassociated FtsZ filaments and lack of Z-ring structure. Yet, microorganisms inhabiting at hadal environment are capable of dividing under extreme HHP condition, and the mechanism behind the pressure resistant cell division remains unknown. Our preliminary results showed that, the FtsZ protein from a hadal obligate piezophilic strain had higher pressure stability and polymerized into filaments under HHP conditions. In this project, by using recently developed high pressure in situ observation and high pressure fixation apparatus, we aim to identify and characterize the amino acids that affect the pressure tolerance of FtsZ protein through in vitro and in vivo analyses. The influence of pressure on the expression and localization of proteins involved in cell division will be analyzed, in order to understand if factors other than the instability of FtsZ filaments impeded Z-ring formation and eventually cell division under HHP conditions. Taken together, the mechanism of HHP adaptation of cell division will be discussed. This study will help deepen our understanding towards the fundamental cellular process of cell division as well as shed light on the distinctive life under extremely HHP environment at the bottom of trenches.