Deep-sea animals live under high pressure and low temperature, but the molecular adaptations to these conditions are not known. Winnikoff et al. have now identified lipid properties that enable different comb jelly (ctenophore) species to adapt to different ocean depths. The authors analyzed tissue from ctenophores collected at different depths from 0 to 4000 m and temperatures at tropical, temperate and Arctic latitudes. Deep-sea ctenophores disintegrated and exhibited loss of lipid membrane structure at atmospheric pressure. Lipids extracted from deep-sea ctenophores formed a lamellar phase under conditions similar to those found deep in the ocean but changed to a nonbilayer phase at lower pressures. The dominant lipid species in high-pressure environments was plasmenyl phosphatidylethanolamine (PPE), making up 73% of phospholipids from deep-sea ctenophores. PPE monolayers have highly negative curvature under atmospheric conditions, curving toward the lipid headgroups, which transition toward zero curvature with greater fluidity at higher pressures. Another adaptation specific to high pressure was an increase in the acyl chain length of lipids, while the number of double bonds in acyl chains was found to increase with both increasing pressure and decreasing temperature. Moreover, the presence of PPE in membranes found in warm, shallow-water-dwelling ctenophores was offset by a greater presence of positive-curvature-inducing lipids and lipids with more saturated acyl chains. In parallel experiments in Escherichia coli, growth rate and survival were less sensitive to pressure for cells synthesizing PPE compared to control cells. By contrast, E. coli synthesizing the lipid phosphatidylcholine, which increases membrane fluidity but has a low curvature, were more sensitive. Thus, an increase in membrane fluidity is not sufficient for pressure adaptation, unlike cold-temperature adaptation; lipids that induce high membrane curvature are required.

Original reference: Science 384, 1482–1488 (2024)

深海动物生活在高压和低温下，但分子对这些条件的适应尚不清楚。温尼科夫等人。现在已经确定了脂质特性，使不同的栉水母（栉水母）物种能够适应不同的海洋深度。作者分析了在 0 至 4000 米不同深度和热带、温带和北极纬度温度下采集的栉水母组织。深海栉水母在大气压下分解并表现出脂质膜结构的损失。从深海栉水母中提取的脂质在与深海相似的条件下形成层状相，但在较低压力下转变为非双层相。高压环境中的主要脂质种类是纤浆酰磷脂酰乙醇胺 (PPE)，占深海栉水母磷脂的 73%。 PPE 单层在大气条件下具有高度负曲率，向脂质头基弯曲，在较高压力下以更大的流动性过渡到零曲率。另一种针对高压的适应性是脂质酰基链长度的增加，同时发现酰基链中双键的数量随着压力的增加和温度的降低而增加。此外，温暖的浅水栉水母的膜中 PPE 的存在被更多的正曲率诱导脂质和具有更多饱和酰基链的脂质所抵消。在大肠杆菌的平行实验中，与对照细胞相比，合成 PPE 的细胞的生长速率和存活率对压力不太敏感。相比之下， E. 合成脂质磷脂酰胆碱的大肠杆菌更敏感，这种脂质磷脂酰胆碱增加了膜的流动性，但曲率较低。因此，与低温适应不同，膜流动性的增加不足以适应压力。需要诱导高膜曲率的脂质。

原始参考文献： Science 384 , 1482–1488 (2024)