PDF(Pubmed)
Abstract：
Archaea adjust the number of cyclopentane rings in their glycerol dibiphytanyl glycerol tetraether (GDGT) membrane lipids as a homeostatic response to environmental stressors such as temperature, pH, and energy availability shifts. However, archaeal expression patterns that correspond with changes in GDGT composition are less understood. Here we characterize the acid and cold stress responses of the thermoacidophilic crenarchaeon Saccharolobus islandicus REY15A using growth rates, core GDGT lipid profiles, transcriptomics and proteomics. We show that both stressors result in impaired growth, lower average GDGT cyclization, and differences in gene and protein expression. Transcription data revealed differential expression of the GDGT ring synthase grsB in response to both acid stress and cold stress. Although the GDGT ring synthase encoded by grsB forms highly cyclized GDGTs with ≥5 ring moieties, S. islandicus grsB upregulation under acidic pH conditions did not correspond with increased abundances of highly cyclized GDGTs. Our observations highlight the inability to predict GDGT changes from transcription data alone. Broader analysis of transcriptomic data revealed that S. islandicus differentially expresses many of the same transcripts in response to both acid and cold stress. These included upregulation of several biosynthetic pathways and downregulation of oxidative phosphorylation and motility. Transcript responses specific to either of the two stressors tested here included upregulation of genes related to proton pumping and molecular turnover in acid stress conditions and upregulation of transposases in cold stress conditions. Overall, our study provides a comprehensive understanding of the GDGT modifications and differential expression characteristic of the acid stress and cold stress responses in S. islandicus.
摘要：
古菌调节其甘油二苯二烷基甘油四醚（GDGT）膜脂质中的环戊烷环的数量，作为对环境压力的稳态响应，例如温度，pH值,和能源可用性的变化。然而,与GDGT组成变化相对应的古细菌表达模式知之甚少。在这里，我们使用生长速率表征了嗜酸热的牙树古菌SaccharobusislandicusREY15A的酸和冷胁迫响应，核心GDGT脂质概况，转录组学和蛋白质组学。我们证明两种压力都会导致增长受损，较低的平均GDGT环化，以及基因和蛋白质表达的差异。转录数据揭示了GDGT环合酶grsB在酸胁迫和冷胁迫下的差异表达。尽管由grsB编码的GDGT环合酶形成具有≥5个环部分的高度环化的GDGT，S.islandicusgrsB在酸性pH条件下的上调与高度环化的GDGT的丰度增加不对应。我们的观察结果强调了无法仅从转录数据预测GDGT变化。对转录组数据的更广泛分析显示，在响应酸和冷胁迫时，岛内沙门氏菌差异表达许多相同的转录本。这些包括几种生物合成途径的上调和氧化磷酸化和运动性的下调。对此处测试的两种应激源中的任何一种具有特异性的转录本响应包括在酸胁迫条件下与质子泵和分子周转有关的基因的上调，以及在冷胁迫条件下转座酶的上调。总的来说,我们的研究提供了一个全面的了解GDGT修饰和差异表达特征的酸胁迫和冷应激反应。
