Carmeli C, Lifshitz Y, Friedberg I
Department of Biochemistry, Tel Aviv University, Israel.
Arch Biochem Biophys. 1991 Aug 1;288(2):516-24. doi: 10.1016/0003-9861(91)90229-c.
Rodobacter capsulatus cells, which were cultured anaerobically in high light intensity, had fewer foldings in the cytoplasmic membrane than those which were grown in lower light intensities. Spheroplast-derived membrane fractions obtained from cells cultured under high light intensity contained a high yield of large right-side-out membrane vesicles. The right-side-out vesicles catalyzed reversible light-induced proton efflux as did intact cells. Nucleotide transport activity was also catalyzed by these membrane vesicles. This activity was indirectly monitored by measurement of photophosphorylation or hydrolysis of externally added diphospho- and triphosphonucleosides. These enzymatic activities occur inside the cytoplasmic membrane of spheroplasts and membrane vesicles and therefore require the transport of the externally added reagents. The indirect measurements of transport were complemented by the demonstration of direct uptake of radiolabeled nucleotides into the membrane vesicles. These data support the suggestion that a nucleotide transporter located in the cytoplasmic membrane of R. capsulatus bacteria mediates these activities.
在高光强度下厌氧培养的荚膜红细菌细胞，其细胞质膜中的折叠比在低光强度下生长的细胞更少。从高光强度下培养的细胞获得的原生质球衍生膜组分含有高产率的大的外翻膜囊泡。外翻囊泡催化可逆的光诱导质子外流，完整细胞也如此。这些膜囊泡也催化核苷酸转运活性。通过测量外部添加的二磷酸和三磷酸核苷的光磷酸化或水解来间接监测该活性。这些酶活性发生在原生质球和膜囊泡的细胞质膜内，因此需要外部添加试剂的运输。通过证明放射性标记核苷酸直接摄取到膜囊泡中，补充了转运的间接测量。这些数据支持这样的观点，即位于荚膜红细菌细胞质膜中的核苷酸转运蛋白介导了这些活性。
