36-membered macrocyclic diether lipid is advantageous for archaea to thrive under the extreme thermal environments
36-membered macrocyclic diether lipid is advantageous for archaea to thrive under the extreme thermal environments
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DOI：
10.1246/bcsj.74.347
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发表时间：
2001-02-01
影响因子：
4
通讯作者：
Kakinuma, K
中科院分区：
文献类型：
--
作者：
Arakawa, K;Eguchi, T;Kakinuma, K
本文通过测定古菌36元大环二醚磷脂36MPC的膜流动性、脂质体质子通透性和脂质体热稳定性，并与非环类DPhyPC及其糖脂衍生物36MGen和DPhycen、蛋黄卵磷脂eggPC和dmpc -胆固醇混合脂质（2:1）进行比较，阐述了该磷脂36MPC作为温度函数的生物物理意义。荧光各向异性测量表明，大环结构通过限制烷基链的运动自由，导致膜间疏水部分的流动性比膜表面的流动性下降更大。引入大环结构也显著降低了质子的渗透率。用6-羧基荧光素（CF）测定脂质体热稳定性表明，36MPC形成的脂质体比DPhyPC形成的脂质体具有更大的热稳定性。糖脂对相应磷脂的存在大大减少了脂质体的CF渗漏。最重要的是，dmpc -胆固醇脂质体在40℃时比36MPC更少渗漏。然而，通过提高温度，这种情况完全逆转了。这表明，环状结构有助于形成稳定的脂质体，特别是在高温下。这些发现清楚地表明，36元大环脂膜在嗜热古菌适应极端环境中起着重要作用。
Described in this paper is the biophysical significance of the archaeal 36-membered macrocyclic diether phospholipid 36MPC as a function of temperature, which was studied by measuring of membrane fluidity, liposomal proton permeability, and liposomal thermostability in comparison with its acyclic counterpart, DPhyPC, their glycolipid derivatives, 36MGen and DPhycen, egg yolk lecithin eggPC, and a mixed lipid of DMPC-cholesterol (2:1). Fluorescence anisotropy measurements indicated that the macrocyclic structure led to a decrease in the fluidity in the inter-membrane hydrophobic part more than in the membrane surface by limiting the motional freedom of the alkyl chains. The proton permeability was also significantly reduced by introducing a macrocyclic structure. Liposomal thermostability measurements using 6-carboxyfluorescein (CF) suggested that 36MPC formed liposomes with greater thermal stability than these of DPhyPC. The presence of glycolipids to the corresponding phospholipids greatly reduced the CF leakage from liposomes. Most importantly, DMPC-cholesterol liposome showed less leakage than 36MPC at 40 degreesC. However, by raising the temperature, this situation was completely reversed. This suggested that the cyclic structure contributed to the formation of stable liposomes, especially at higher temperatures. These findings clearly demonstrate that the 36-membered macrocyclic lipid membrane plays an important role for the thermophilic archaea to adapt to extreme environments.