The past and present of sodium energetics: May the sodium-motive force be with you
The past and present of sodium energetics: May the sodium-motive force be with you
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DOI：
10.1016/j.bbabio.2008.04.028
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发表时间：
2008-07-01
影响因子：
4.3
通讯作者：
Galperin, Michael Y.
中科院分区：
文献类型：
--
作者：
Mulkidjanian, Armen Y.;Dibrov, Pavel;Galperin, Michael Y.
所有活细胞都会定期排出 Na+ 离子，从而使细胞质中的 Na+ 浓度保持低于周围环境。在绝大多数细菌以及线粒体和叶绿体中，Na+的输出是以牺牲质子动力为代价的。然而，一些细菌拥有 Na+（钠动力）跨膜电化学梯度的主要发生器。这些初级 Na+ 泵传统上被视为对高外部 pH 值或高温的适应。然而，随后的研究揭示了多种非极端微生物（例如海洋细菌和某些细菌病原体）的初级钠泵机制。此外，许多嗜碱性物质和超嗜热物质依赖 H+（而不是 Na+）作为偶联离子。我们在此回顾了理解钠动力作用的最新进展，包括（i）钠动力作为能量中间体的进化首要性的结论，（ii）从Na+转换为H+作为耦合离子的机制、进化优势和局限性，以及（iii）某些病原菌仍然依赖钠动力的可能原因。 (C) 2008 Elsevier B.V. All Fights 保留。
All living cells routinely expel Na+ ions, maintaining lower concentration of Na+ in the cytoplasm than in the surrounding milieu. In the vast majority of bacteria, as well as in mitochondria and chloroplasts, export of Na+ occurs at the expense of the proton-motive force. Some bacteria, however, possess primary generators of the transmembrane electrochemical gradient of Na+ (sodium-motive force). These primary Na+ pumps have been traditionally seen as adaptations to high external pH or to high temperature. Subsequent studies revealed, however, the mechanisms for primary sodium pumping in a variety of non-extremophiles, such as marine bacteria and certain bacterial pathogens. Further, many alkaliphiles and hyperthermophiles were shown to rely on H+, not Na+, as the coupling ion. We review here the recent progress in understanding the role of sodium-motive force, including (i) the conclusion on evolutionary primacy of the sodium-motive force as energy intermediate, (ii) the mechanisms, evolutionary advantages and limitations of switching from Na+ to H+ as the coupling ion, and (iii) the possible reasons why certain pathogenic bacteria Still rely on the sodium-motive force. (C) 2008 Elsevier B.V. All Fights reserved.