Nitschke Wolfgang, McGlynn Shawn E, Milner-White E James, Russell Michael J
Laboratoire de Bioénergétique et Ingénierie des Protéines, Marseille Cedex 20, France.
Biochim Biophys Acta. 2013 Aug-Sep;1827(8-9):871-81. doi: 10.1016/j.bbabio.2013.02.008. Epub 2013 Feb 26.
Many metalloenzymes that inject and extract reducing equivalents at the beginning and the end of electron transport chains involved in chemiosmosis are suggested, through phylogenetic analysis, to have been present in the Last Universal Common Ancestor (LUCA). Their active centres are affine with the structures of minerals presumed to contribute to precipitate membranes produced on the mixing of hydrothermal solutions with the Hadean Ocean 4 billion years ago. These mineral precipitates consist of transition element sulphides and oxides such as nickelian mackinawite ([Fe>Ni]2S2), a nickel-bearing greigite (FeSS[Fe3NiS4]SSFe), violarite (NiSS[Fe2Ni2S4]SSNi), a molybdenum bearing complex (Mo(IV/VI)2Fe3S(0/2-)9) and green rust or fougerite (~Fe(II)Fe(III)(OH)4OH). They may be respectively compared with the active centres of Ni-Fe hydrogenase, carbon monoxide dehydrogenase (CODH), acetyl coenzyme-A synthase (ACS), the complex iron-sulphur molybdoenzyme (CISM) superfamily and methane monooxygenase (MMO). With the look of good catalysts - a suggestion that gathers some support from prebiotic hydrothermal experimentation - and sequestered by short peptides, they could be thought of as the original building blocks of proto-enzyme active centres. This convergence of the makeup of the LUCA-metalloenzymes with mineral structure and composition of hydrothermal precipitates adds credence to the alkaline hydrothermal (chemiosmotic) theory for the emergence of life, specifically to the possibility that the first metabolic pathway - the acetyl CoA pathway - was initially driven from either end, reductively from CO2 to CO and oxidatively and reductively from CH4 through to a methane thiol group, the two entities assembled with the help of a further thiol on a violarite cluster sequestered by peptides. By contrast, the organic coenzymes were entirely a product of the first metabolic pathways. This article is part of a Special Issue entitled: Metals in Bioenergetics and Biomimetics Systems.
通过系统发育分析表明，许多在化学渗透作用所涉及的电子传递链起始和末端注入及提取还原当量的金属酶，在最后的共同祖先（LUCA）中就已存在。它们的活性中心与据推测在约40亿年前热液溶液与冥古宙海洋混合时有助于沉淀膜形成的矿物质结构相似。这些矿物沉淀由过渡元素硫化物和氧化物组成，如镍镁铁闪石（[Fe>Ni]2S2）、含镍硫复铁矿（FeSS[Fe3NiS4]SSFe）、紫硫镍矿（NiSS[Fe2Ni2S4]SSNi）、含钼络合物（Mo(IV/VI)2Fe3S(0/2-)9）以及绿锈或镁铁水滑石（Fe(II)Fe(III)(OH)4OH）。它们可分别与镍铁氢化酶、一氧化碳脱氢酶（CODH）、乙酰辅酶A合成酶（ACS）、铁硫钼酶复合超家族（CISM）和甲烷单加氧酶（MMO）的活性中心相比较。从其作为良好催化剂的外观来看——这一观点从益生元热液实验中获得了一些支持——并且被短肽隔离，它们可被视为原酶活性中心的原始组成部分。LUCA金属酶的组成与热液沉淀物的矿物结构和成分的这种趋同，为生命起源的碱性热液（化学渗透）理论增添了可信度，特别是关于第一个代谢途径——乙酰辅酶A途径——最初可能从两端驱动的可能性，一端是从二氧化碳还原为一氧化碳，另一端是从甲烷通过氧化和还原反应生成甲硫醇基团，这两个实体在由肽隔离的紫硫镍矿簇上借助另一种硫醇组装而成。相比之下，有机辅酶完全是第一个代谢途径的产物。本文是名为《生物能量学和仿生系统中的金属》的特刊的一部分。
