Tokuda H
Institute of Applied Microbiology, University of Tokyo, Japan.
J Bioenerg Biomembr. 1989 Dec;21(6):693-704. doi: 10.1007/BF00762687.
The marine bacterium Vibrio alginolyticus was found to possess the respiratory Na+ pump that generates an electrochemical potential of Na+, which plays a central role in bioenergetics of V. alginolyticus, as a direct result of respiration. Mutants defective in the Na+ pump revealed that one of the two kinds of NADH: quinone oxidoreductase requires Na+ for activity and functions as the Na+ pump. The Na+ pump composed of three subunits was purified and reconstituted into liposomes. Generation of membrane potential by the reconstituted proteoliposomes required Na+. The respiratory Na+ pump coupled to the NADH: quinone oxidoreductase was found in wide varieties of Gram-negative marine bacteria belonging to the genera Alcaligenes, Alteromonas, and Vibrio, and showed a striking similarity in the mode of electron transfer and enzymic properties. Na+ extrusion seemed to be coupled to a dismutation reaction, which leads to the formation of quinol and quinone from semiquinone radical.
人们发现海洋细菌溶藻弧菌拥有呼吸性钠离子泵，该泵可产生钠离子的电化学势，呼吸作用直接导致其在溶藻弧菌的生物能量学中发挥核心作用。钠离子泵缺陷型突变体表明，两种NADH：醌氧化还原酶中的一种需要钠离子来发挥活性，并作为钠离子泵发挥作用。由三个亚基组成的钠离子泵被纯化并重组到脂质体中。重组的蛋白脂质体产生膜电位需要钠离子。与NADH：醌氧化还原酶偶联的呼吸性钠离子泵在多种属于产碱菌属、交替单胞菌属和弧菌属的革兰氏阴性海洋细菌中均有发现，并且在电子传递模式和酶学性质上表现出惊人的相似性。钠离子的排出似乎与歧化反应偶联，该反应导致从半醌自由基形成喹醇和醌。
