Müller V, Lemker T, Lingl A, Weidner C, Coskun U, Grüber G
Molecular Microbiology and Bioenergetics, Institute of Molecular Biosciences, Johann Wolfgang Goethe University Frankfurt/Main, Campus Riedberg, Frankfurt a. Main, Germany.
J Mol Microbiol Biotechnol. 2005;10(2-4):167-80. doi: 10.1159/000091563.
Archaea are a heterogeneous group of microorganisms that often thrive under harsh environmental conditions such as high temperatures, extreme pHs and high salinity. As other living cells, they use chemiosmotic mechanisms along with substrate level phosphorylation to conserve energy in form of ATP. Because some archaea are rooted close to the origin in the tree of life, these unusual mechanisms are considered to have developed very early in the history of life and, therefore, may represent first energy-conserving mechanisms. A key component in cellular bioenergetics is the ATP synthase. The enzyme from archaea represents a new class of ATPases, the A1A0 ATP synthases. They are composed of two domains that function as a pair of rotary motors connected by a central and peripheral stalk(s). The structure of the chemically-driven motor (A1) was solved by small-angle X-ray scattering in solution, and the structure of the first A1A0 ATP synthases was obtained recently by single particle analyses. These studies revealed novel structural features such as a second peripheral stalk and a collar-like structure. In addition, the membrane-embedded electrically-driven motor (A0) is very different in archaea with sometimes novel, exceptional subunit composition and coupling stoichiometries that may reflect the differences in energy-conserving mechanisms as well as adaptation to temperatures at or above 100 degrees C.
古菌是一类异质的微生物群体，它们常常在高温、极端pH值和高盐度等恶劣环境条件下茁壮成长。与其他活细胞一样，它们利用化学渗透机制以及底物水平磷酸化作用来以ATP的形式保存能量。由于一些古菌在生命之树中处于靠近起源的位置，这些不同寻常的机制被认为是在生命历史的早期就已发展起来，因此可能代表了最初的能量保存机制。细胞生物能量学中的一个关键组成部分是ATP合酶。来自古菌的这种酶代表了一类新的ATP酶，即A1A0 ATP合酶。它们由两个结构域组成，这两个结构域作为一对通过中央和外周柄连接的旋转马达发挥作用。化学驱动马达（A1）的结构通过溶液中的小角X射线散射得以解析，而首个A1A0 ATP合酶的结构最近通过单颗粒分析获得。这些研究揭示了一些新的结构特征，如第二个外周柄和一个衣领状结构。此外，膜嵌入的电驱动马达（A0）在古菌中差异很大，其亚基组成和偶联化学计量有时很新颖且独特，这可能反映了能量保存机制的差异以及对100摄氏度及以上温度的适应。
