Elucidating the lipidome of Archaea is essential to understand their tolerance to extreme environmental conditions. Previous characterizations of the lipid composition of Pyrococcus species, a model genus of hyperthermophilic archaea belonging to the Thermococcales order, led to conflicting results, which hindered the comprehension of their membrane structure and the putative adaptive role of their lipids. In an effort to clarify the lipid composition data of the Pyrococcus genus, we thoroughly investigated the distribution of both the core lipids (CL) and intact polar lipids (IPL) of the model Pyrococcus furiosus and, for the first time, of Pyrococcus yayanosii, the sole obligate piezophilic hyperthermophilic archaeon known to date. We showed a low diversity of IPL in the lipid extract of P. furiosus, which nonetheless allowed the first report of phosphatidyl inositol-based glycerol mono- and trialkyl glycerol tetraethers. With up to 13 different CL structures identified, the acid methanolysis of Pyrococcus furiosus revealed an unprecedented CL diversity and showed strong discrepancies with the IPL compositions reported here and in previous studies. By contrast, P. yayanosii displayed fewer CL structures but a much wider variety of polar heads. Our results showed severe inconsistencies between IPL and CL relative abundances. Such differences highlight the diversity and complexity of the Pyrococcus plasma membrane composition and demonstrate that a large part of its lipids remains uncharacterized. Reassessing the lipid composition of model archaea should lead to a better understanding of the structural diversity of their lipidome and of their physiological and adaptive functions.

中文翻译：

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火球菌模型种中新的完整的极性和核心脂质成分，激烈热球菌和矢车菊，揭示了热球菌中最大的脂质多样性。

阐明古细菌的脂质组对于了解它们对极端环境条件的耐受性至关重要。嗜热球菌属高温嗜热古菌的一个模型属热球菌物种的脂质组成的先前表征导致相互矛盾的结果，这阻碍了对其膜结构的理解以及其脂质的假定的适应性作用。为了弄清火球菌属的脂质组成数据，我们彻底研究了火球菌（Pyrococcus furiosus）模型和首次发现的火球菌（Yyrococcus yayanosii）的核心脂质（CL）和完整极性脂质（IPL）的分布，这是迄今为止已知的唯一专职的嗜压性超嗜热古细菌。我们显示在P. furiosus的脂质提取物中IPL的多样性低，尽管如此，这使得首次报道了基于磷脂酰肌醇的甘油单-和三烷基甘油四醚。鉴定出多达13种不同的CL结构后，激烈热球菌的酸性甲醇分解显示出前所未有的CL多样性，并且与此处和以前的研究中报道的IPL组成存在明显差异。相比之下，P。yayanosii显示出较少的CL结构，但种类繁多的极头。我们的结果表明IPL和CL相对丰度之间存在严重不一致。这种差异突出了火球菌的多样性和复杂性。质膜组成，并证明其大部分脂质仍未鉴定。重新评估模型古细菌的脂质组成应有助于更好地了解其脂质组的结构多样性及其生理和适应功能。