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首页> 外文期刊>Journal of bacteriology >Role of Na+ cycle in cell volume regulation of Mycoplasma gallisepticum.
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Role of Na+ cycle in cell volume regulation of Mycoplasma gallisepticum.

机译：Na +循环在鸡毒支原体细胞体积调节中的作用。

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The mechanism for the extrusion of Na+ from Mycoplasma gallisepticum cells was examined. Na+ efflux from cells was studied by diluting 22Na+-loaded cells into an isoosmotic NaCl solution and measuring the residual 22Na+ in the cells. Uphill 22Na+ efflux was found to be glucose dependent and linear with time over a 60-s period and showed almost the same rate in the pH range of 6.5 to 8.0. 22Na+ efflux was markedly inhibited by dicyclohexylcarbodiimide (DCCD, 10 microM), but not by the proton-conducting ionophores SF6847 (0.5 microM) or carbonyl cyanide m-chlorophenylhydrazone (CCCP, 10 microM) over the entire pH range tested. An ammonium diffusion potential and a pH gradient were created by diluting intact cells or sealed membrane vesicles of M. gallisepticum loaded with NH4Cl into a choline chloride solution. The imposed H+ gradient (inside acid) was not affected by the addition of either NaCl or KCl to the medium. Dissipation of the proton motive force by CCCP had no effect on the growth of M. gallisepticum in the pH range of 7.2 to 7.8 in an Na+-rich medium. Additionally, energized M. gallisepticum cells were stable in an isoosmotic NaCl solution, even in the presence of proton conductors, whereas nonenergized cells tended to swell and lyse. These results show that in M. gallisepticum Na+ movement was neither driven nor inhibited by the collapse of the electrochemical gradient of H+, suggesting that in this organism Na+ is extruded by an electrogenic primary Na+ pump rather than by an Na+-H+ exchange system energized by the proton motive force.
机译：研究了从鸡支原体细胞中挤出Na +的机制。通过将加载22Na +的细胞稀释到等渗NaCl溶液中并测量细胞中残留的22Na +，来研究细胞的Na +外排。发现上坡的22Na +流出是葡萄糖依赖性的，并且在60秒内随时间呈线性变化，并且在6.5至8.0的pH范围内显示出几乎相同的速率。在整个测试pH范围内，二环己基碳二亚胺（DCCD，10 microM）显着抑制了22Na +的外排，但质子传导离子载体SF6847（0.5 microM）或羰基氰化物间氯苯hydr（CCCP，10 microM）没有明显抑制22Na +的流出。通过将装载有NH4Cl的鸡败血支原体的完整细胞或密封膜囊泡稀释到氯化胆碱溶液中，可产生铵扩散电位和pH梯度。施加的H +梯度（内部酸）不受向培养基中添加NaCl或KCl的影响。 CCCP耗散的质子原动力在富Na +的pH范围内（7.2至7.8）对鸡毒支原体的生长没有影响。此外，即使在质子导体存在的情况下，通电的鸡毒支原体细胞在等渗的NaCl溶液中也很稳定，而未通电的细胞则倾向于溶胀和溶解。这些结果表明，在鸡毒支原体中，Na +的移动既不受H +的电化学梯度的破坏驱动，也没有受到抑制，这表明在该生物中，Na +是通过电原代Na +泵而不是通过由Na +激发的Na +-H +交换系统挤出的。质子原动力。

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