超嗜热嗜压古菌Pyrococcus yayanosii中多模块基因组岛PYG1的功能和相关适应性研究

Thermococcales is one of the predominant group in deep-sea microbiological community. Research on the mobility of genomic island will provide clues for the co-evolution process between this group of hyperthermophilic archaea and its environment. Pyrococcus yayanosii CH1 was isolated from the deepest hydrothermal vent and is the only species with strict barophilic characteristics in Thermococcales. The environmental selective pressure on the plasticity of CH1’s genome is an attractive scientific question. This proposal target on the biological functions of the biggest genomic island identified in CH1’s genome. By monitoring the excision frequency of PYG1, causal relationship between mobility of PYG1 and fluctuation of the environmental factors such as temperature and hydrostatic-press. Using gene knockout and complementation techniques, the functions of different genetic modules of PYG1 will be examined. The role of the putative toxin-antitoxin system that is supposed to play in keeping the genomic island and involving in global regulation will be investigated. In according to the increasing demand of amino acid, the importance of acquiring the glutamine amidotransferase, which are common in PYG1 and an endogenous plasmid in another barophilic species in Thermococcales, will be questioned for a systems-biological view on the environmental adaptation mechanism used in this hyperthermophilic and barophilic archaea.

热球菌目古菌是深海热液环境微生物群落中的优势类群之一。对此类古菌基因组中可移动性基因组岛进行研究，将为理解超嗜热古菌和环境的协同演化过程提供线索。Pyrococcus yayanosii CH1是热球菌目中唯一严格嗜压的超嗜热古菌，环境压力对其基因组可塑性的影响是重要的科学问题。本研究以P. yayanosii 中最大的基因组岛（PYG1）为研究对象，测定不同培养条件下PYG1的环出频率，分析PYG1可移动性和温度压力等环境因子变化的联系；通过基因敲除和回补，解析PYG1中各个模块的生理功能。阐明PYG1中毒素-抗毒素模块在维持基因组岛存在和参与环境胁迫应激中的作用。针对高静水压胁迫增加此类超嗜热古菌对氨基酸的需求，对P. yayanosii CH1中PYG1内和另一个嗜压古菌内源质粒上共有的氨基转移酶的功能进行研究，在系统生物学层次上解释此类超嗜热嗜压微生物的环境适应性。

热球菌目古菌是深海热液环境微生物群落中的优势类群之一。对此类古菌基因组中可移动性基因组岛进行研究，将为理解超嗜热古菌和环境的协同演化过程提供线索。本研究以嗜压的超嗜热古菌P. yayanosii 中最大的基因组岛（PYG1）为研究对象，证实了此基因组岛为整合于基因组tRNA-Gln中特点位点的可移动元件。以PYG1来源的整合酶为元件构建了新型的位点特异性整合载体；将P. yayanosii中受高静水压诱导的启动子和超嗜热古菌热球菌的毒素元件进行组合，利用此类内源性毒素选择标记，构建了新型高效的基因敲除系统。通过基因敲除和回补，证实了PYG1中携带的毒素-抗毒素系统为有功能性的元件。确定基因组岛PYG1及其中的氨基转移酶（PYCH_15260）与菌株的高压适应性有关。通过定量蛋白质组学分析，初步解释了基因岛中的氨基转移酶（PYCH_15260）可能参与了高静水压下嘌呤的从头合成途径而影响P. yayanosii的环境适应性。