Lane Nick
Department of Genetics, Evolution and Environment, University College London, London, UK.
Bioessays. 2017 Jun;39(6). doi: 10.1002/bies.201600217. Epub 2017 May 15.
Chemiosmotic coupling - the harnessing of electrochemical ion gradients across membranes to drive metabolism - is as universally conserved as the genetic code. As argued previously in these pages, such deep conservation suggests that ion gradients arose early in evolution, and might have played a role in the origin of life. Alkaline hydrothermal vents harbour pH gradients of similar polarity and magnitude to those employed by modern cells, one of many properties that make them attractive models for life's origin. Their congruence with the physiology of anaerobic autotrophs that use the acetyl CoA pathway to fix CO gives the alkaline vent model broad appeal to biologists. Recently, however, a paper by Baz Jackson criticized the hypothesis, concluding that natural pH gradients were unlikely to have played any role in the origin of life. Unfortunately, Jackson mainly criticized his own interpretations of the theory, not what the literature says. This counterpoint is intended to set the record straight.
化学渗透偶联——利用跨膜电化学离子梯度驱动新陈代谢——与遗传密码一样具有普遍的保守性。正如此前在这些页面中所讨论的，这种深度保守性表明离子梯度在进化早期就已出现，并且可能在生命起源中发挥了作用。碱性热液喷口具有与现代细胞所利用的极性和大小相似的pH梯度，这是使其成为生命起源有吸引力模型的众多特性之一。它们与利用乙酰辅酶A途径固定二氧化碳的厌氧自养生物的生理学一致性，使得碱性喷口模型受到生物学家的广泛关注。然而，最近巴兹·杰克逊的一篇论文对这一假说提出了批评，得出自然pH梯度在生命起源中不太可能发挥任何作用的结论。不幸的是，杰克逊主要批评的是他自己对该理论的解读，而非文献中的说法。这篇回应旨在澄清事实。
