Prowe S G, van de Vossenberg J L, Driessen A J, Antranikian G, Konings W N
Technical Microbiology, Biotechnology I, Technical University Hamburg-Harburg, Germany.
J Bacteriol. 1996 Jul;178(14):4099-104. doi: 10.1128/jb.178.14.4099-4104.1996.
Strain LBS3 is a novel anaerobic thermoalkaliphilic bacterium that grows optimally at pH 9.5 and 50 degrees C. Since a high concentration of Na+ ions is required for growth, we have analyzed the primary bioenergetic mechanism of energy transduction in this organism. For this purpose, a method was devised for the isolation of right-side-out membrane vesicles that are functional for the energy-dependent uptake of solutes. A strict requirement for Na+ was observed for the uptake of several amino acids, and in the case of L-leucine, it was concluded that amino acid uptake occurs in symport with Na+ ions. Further characterization of the leucine transport system revealed that its pH and temperature optima closely match the conditions that support the growth of strain LBS3. The ATPase activity associated with inside-out membrane vesicles was found to be stimulated by both Na+ and Li+ ions. These data suggest that the primary mechanism of energy transduction in the anaerobic thermoalkaliphilic strain LBS3 is dependent on sodium cycling. The implications of this finding for the mechanism of intracellular pH regulation are discussed.
菌株LBS3是一种新型厌氧嗜热嗜碱细菌，在pH 9.5和50摄氏度条件下生长最佳。由于生长需要高浓度的Na+离子，我们分析了该生物体中能量转导的主要生物能量机制。为此，设计了一种分离对溶质能量依赖性摄取具有功能的外翻膜囊泡的方法。观察到几种氨基酸的摄取对Na+有严格要求，就L-亮氨酸而言，得出氨基酸摄取与Na+离子协同转运的结论。亮氨酸转运系统的进一步表征表明，其最适pH和温度与支持菌株LBS3生长的条件密切匹配。发现与内翻膜囊泡相关的ATP酶活性受到Na+和Li+离子的刺激。这些数据表明，厌氧嗜热嗜碱菌株LBS3中能量转导的主要机制依赖于钠循环。讨论了这一发现对细胞内pH调节机制的影响。
