Energy flux controls tetraether lipid cyclization in Sulfolobus acidocaldarius
Energy flux controls tetraether lipid cyclization in Sulfolobus acidocaldarius
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DOI：
10.1101/744623
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发表时间：
2019-08
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影响因子：
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通讯作者：
A. Zhou;Y. Weber;B. Chiu;F. Elling;A. Cobban;A. Pearson;W. Leavitt
中科院分区：
文献类型：
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作者：
A. Zhou;Y. Weber;B. Chiu;F. Elling;A. Cobban;A. Pearson;W. Leavitt
微生物根据环境提示调节其细胞膜的组成。许多古生菌通过调节其甘油二双植酸甘油四醚(GDGT)脂核内的环状基团的数量来维持其膜的流动性和通透性。环化的GDGT增加了膜的堆积和稳定性，这已被证明有助于细胞在温度和pH的变化中生存。然而，这种环化的程度也因生长阶段和电子受体或给体的限制而不同。这些观察结果表明，能量代谢与膜成分之间存在着关系。在连续培养的嗜热嗜酸性硫杆菌(DSM 639)中，GDGT的平均环化程度随着倍增时间的增加而增加。这与中营养亚硝酸菌SCM1的行为是一致的。综上所述，这些结果表明，古生菌的GDGT分布可以随着电子供体通量和能量可获得性的变化而变化，与pH或温度无关。因此，基于GDGT的古环境重建捕获了微生物可用的能量，其中包括温度和pH的波动以及电子供体和受体的可用性。古生菌调节膜成分和堆积的能力可能是使其能够在能量胁迫期间存活的重要策略。意义陈述微生物脂膜保护细胞并将其与环境隔离，同时调节能量和营养物质流向内部的代谢反应中心。我们使用一个在酸性温泉中茁壮成长的经过充分研究的古生物证明了膜脂作为能量通量的函数变化，并观察到随着能量变得更加有限，膜填充的增加。这些观察结果与利用低温、中性pH、海洋古细菌进行的恒化器实验是一致的。这一策略似乎调节膜的动态平衡在GDGT产生谱系中是常见的，表明不同的类群调整膜组成以响应慢性能量胁迫。
Microorganisms regulate the composition of their membranes in response to environmental cues. Many archaea maintain the fluidity and permeability of their membranes by adjusting the number of cyclic moieties within the cores of their glycerol dibiphytanyl glycerol tetraether (GDGT) lipids. Cyclized GDGTs increase membrane packing and stability, which has been shown to help cells survive shifts in temperature and pH. However, the extent of this cyclization also varies with growth phase and electron acceptor or donor limitation. These observations indicate a relationship between energy metabolism and membrane composition. Here we show that the average degree of GDGT cyclization increases with doubling time in continuous cultures of the thermoacidophile Sulfolobus acidocaldarius (DSM 639). This is consistent with the behavior of a mesoneutrophile, Nitrosopumilus maritimus SCM1. Together, these results demonstrate that archaeal GDGT distributions can shift in response to electron donor flux and energy availability, independent of pH or temperature. Paleoenvironmental reconstructions based on GDGTs thus capture the energy available to microbes, which encompasses fluctuations in temperature and pH, as well as electron donor and acceptor availability. The ability of Archaea to adjust membrane composition and packing may be an important strategy that enables survival during episodes of energy stress. Significance Statement Microbial lipid membranes protect and isolate a cell from its environment while regulating the flow of energy and nutrients to metabolic reaction centers within. We demonstrate that membrane lipids change as a function of energy flux using a well-studied archaeon that thrives in acidic hot springs and observe an increase in membrane packing as energy becomes more limited. These observations are consistent with chemostat experiments utilizing a low temperature, neutral pH, marine archaeon. This strategy appears to regulate membrane homeostasis is common across GDGT-producing lineages, demonstrating that diverse taxa adjust membrane composition in response to chronic energy stress.