Indiana University School of Medicine-South Bend, Raclin Carmichael Hall, 1234 Notre Dame Ave., South Bend, IN 46617, USA.
Comp Biochem Physiol A Mol Integr Physiol. 2021 Feb;252:110824. doi: 10.1016/j.cbpa.2020.110824. Epub 2020 Oct 30.
"Nothing in biology makes sense except in the light of evolution" (Theodosius Dobzhansky) and "For such a large number of problems there will be some animal of choice, or a few such animals, on which it can be most conveniently studied" (August Krogh); dictums that can be used to illustrate the past and provide a guide to the future. Although sulfur was integral in the origin of life, and nearly seven-eights of subsequent evolution, its physiological importance is largely overlooked because much of contemporary life it is based on oxygen and the adherent problems associated with oxygen deficit (hypoxia) or excess (oxidative stress). This graphical review will summarize sulfur's role in evolution and make a case that many of the regulatory activities attributed to oxygen and reactive oxygen species (ROS) can also be ascribed to reactive sulfur species (RSS). ROS and RSS are chemically similar and signal via identical cysteine residues on regulatory proteins and have identical downstream effector responses. Antioxidant mechanisms, generally attributed to the advent of an oxic existence, actually appeared over 2 billion years prior, in sulfur metabolizing organisms. Recent evidence suggests they are active in sulfur metabolism to this day. Understanding these aspects of ROS and RSS suggests that alternative mechanisms for oxidant/antioxidant pathways and therapies must be considered. As oxygen and reduced sulfur do not coexist, either in cells or the environment, it is also important to design and conduct experiments in oxygen levels that are physiologically relevant. For every experiment there are optimal conditions under which it must be studied.
"没有生物学的东西是有意义的，除非在进化的光线下"（Theodosius Dobzhansky）和 "对于如此多的问题，将会有一些选择的动物，或者少数这样的动物，在其上可以最方便地研究"（August Krogh）；这些格言可以用来说明过去，并为未来提供指导。尽管硫在生命起源和随后的进化中起着至关重要的作用，但由于现代生命主要基于氧气，以及与氧气不足（缺氧）或过量（氧化应激）相关的问题，硫的生理重要性在很大程度上被忽视了。这篇图形综述将总结硫在进化中的作用，并提出一个观点，即许多归因于氧和活性氧物种（ROS）的调节活动也可以归因于活性硫物种（RSS）。ROS 和 RSS 在化学上相似，通过调节蛋白上相同的半胱氨酸残基进行信号传递，并且具有相同的下游效应器反应。抗氧化机制，通常归因于氧化存在的出现，实际上早在 20 多亿年前，在硫代谢生物体中就已经出现了。最近的证据表明，它们至今仍在参与硫代谢。理解 ROS 和 RSS 的这些方面表明，必须考虑替代氧化剂/抗氧化剂途径和治疗方法的机制。由于氧气和还原硫在细胞或环境中都不能共存，因此在生理相关的氧气水平下设计和进行实验也很重要。对于每个实验，都有其必须在最佳条件下进行研究的条件。
