Gogarten J P, Rausch T, Bernasconi P, Kibak H, Taiz L
Biology Department, University of California, Santa Cruz 95064.
Z Naturforsch C J Biosci. 1989 Jul-Aug;44(7-8):641-50. doi: 10.1515/znc-1989-7-816.
The classification of methanogenic bacteria as archaebacteria based on 16 s rRNA sequence analysis is currently in dispute. To provide an alternative molecular marker, the polymerase chain reaction technique was used to amplify a 930 bp fragment of Methanococcus thermolithotrophicus genomic DNA corresponding to the catalytic domain of the membrane H+-ATPase. The deduced amino acid sequence was 54-58% identical to the approximately 70 kDa subunits of Sulfolobus acidocaldarius and the eukaryotic vacuolar-type H+-ATPase, and only 29% identical to the beta subunit of the eubacterial-type F0F1-ATPases. Interestingly, a highly conserved aspartate residue in the phosphorylation domain of E1E2-ATPases (P-type) is conserved in the Methanococcus sequence, but is absent from all other known vacuolar and F0F1-ATPases. This suggests that the H+-ATPase of M. thermolithotrophicus, like that of M. voltae, may have a phosphorylated intermediate, despite belonging to the vacuolar-type class of proton pumps. Phylogenetic analysis using Felsenstein's maximum likelihood method and Lake's evolutionary parsimony method confirmed that the H+-ATPases of the two archaebacteria, Methanococcus and Sulfolobus, when compared to eukaryotic vacuolar-type ATPases and eubacterial F0F1-ATPases, form a monophyletic group.
基于16 s rRNA序列分析将产甲烷细菌归类为古细菌目前存在争议。为了提供一种替代分子标记，采用聚合酶链反应技术扩增了嗜热自养甲烷球菌基因组DNA的一个930 bp片段，该片段对应于膜H⁺-ATP酶的催化结构域。推导的氨基酸序列与嗜酸硫化叶菌约70 kDa亚基和真核液泡型H⁺-ATP酶有54 - 58%的同一性，与真细菌型F₀F₁-ATP酶的β亚基只有29%的同一性。有趣的是，E₁E₂-ATP酶（P型）磷酸化结构域中一个高度保守的天冬氨酸残基在甲烷球菌序列中保守，但在所有其他已知的液泡型和F₀F₁-ATP酶中不存在。这表明嗜热自养甲烷球菌的H⁺-ATP酶，与沃氏甲烷球菌的一样，可能有一个磷酸化中间体，尽管它属于质子泵的液泡型类别。使用费尔森斯坦最大似然法和莱克进化简约法进行的系统发育分析证实，与真核液泡型ATP酶和真细菌F₀F₁-ATP酶相比，两种古细菌甲烷球菌和硫化叶菌的H⁺-ATP酶形成一个单系群。
