Smigán P, Majerník A, Greksák M
Institute of Animal Biochemistry and Genetics, Slovak Academy of Sciences, Ivanka pri Dunaji.
FEBS Lett. 1994 Jun 27;347(2-3):190-4. doi: 10.1016/0014-5793(94)00535-4.
Rhodamine 6G (3 microM) effectively inhibited delta pH-driven ATP synthesis in Methanobacterium thermoautotrophicum while delta pNa-driven ATP synthesis was not affected by it. Rhodamine 6G inhibited Mg(2+)-stimulated ATPase activity of membrane vesicles prepared from these cells but the ATPase catalytic sector detached from the membrane was insensitive to this inhibitor. Methanogenesis-driven ATP synthesis at pH 6.8 of cells grown in the presence of 50 mM NaCl was inhibited by rhodamine 6G both in the presence of 5 mM and 50 mM NaCl. On the other hand, the methanogenesis-driven ATP synthesis at pH 8.0 of cells grown in the presence of 50 mM NaCl was slightly inhibited by rhodamine 6G in the presence of 5 mM NaCl and was not inhibited at all in the presence of 50 mM NaCl. The growth experiments have shown that cells of Methanobacterium thermoautotrophicum can grow under alkaline conditions even in the presence of rhodamine 6G and of high NaCl concentration when the growth media were inoculated with the cells which had been grown in the presence of 50 mM NaCl. These results indicate that sodium-motive force-driven ATP synthase in Methanobacterium thermoautotrophicum operates effectively in alkaline conditions and it might be the sole ATP synthesizing system when the proton-motive force-supported ATP synthesis is inhibited by rhodamine 6G.
罗丹明6G（3微摩尔）能有效抑制嗜热自养甲烷杆菌中由质子动力势驱动的ATP合成，而由钠离子动力势驱动的ATP合成不受其影响。罗丹明6G抑制了从这些细胞制备的膜囊泡的镁离子刺激的ATP酶活性，但从膜上分离的ATP酶催化部分对这种抑制剂不敏感。在50 mM氯化钠存在下生长的细胞，在pH 6.8时，甲烷生成驱动的ATP合成在5 mM和50 mM氯化钠存在下均被罗丹明6G抑制。另一方面，在50 mM氯化钠存在下生长的细胞，在pH 8.0时，在5 mM氯化钠存在下，甲烷生成驱动的ATP合成被罗丹明6G轻微抑制，而在50 mM氯化钠存在下则完全不被抑制。生长实验表明，当用在50 mM氯化钠存在下生长的细胞接种生长培养基时，嗜热自养甲烷杆菌的细胞即使在存在罗丹明6G和高氯化钠浓度的碱性条件下也能生长。这些结果表明，嗜热自养甲烷杆菌中由钠离子动力势驱动的ATP合酶在碱性条件下能有效发挥作用，并且当由质子动力势支持的ATP合成被罗丹明6G抑制时，它可能是唯一的ATP合成系统。
