Differential cytochrome content and reductase activity in Geospirillum barnesii strain SeS3
Differential cytochrome content and reductase activity in Geospirillum barnesii strain SeS3
复制标题
巴氏地螺菌SeS3菌株细胞色素含量和还原酶活性的差异
作者：
J. Stolz;T. Gugliuzza;J. S. Blum;R. Oremland;F. Murillo
摘要研究了以硫代硫酸盐、硝酸盐、硒酸盐和富马酸盐为末端电子受体的异化硒酸盐还原菌Geocellum barnesii菌株SeS 3的蛋白质组成、细胞色素含量和还原酶活性。7个高分子量膜蛋白（105.3，90.3，82.6，70.2，67.4，61.1，和57.3 kDa）的SDS-PAGE比较表明，它们的检测依赖于所使用的末端电子受体。硫代硫酸盐上生长的细胞膜组分含有70.2 kDa的C-型细胞色素，在552，522和421 nm处具有最大吸收。一个61.1 kDa的C型细胞色素，在552，523和423 nm处的最大吸收被认为是在硝酸盐上生长的细胞膜组分。没有c型细胞色素中检测到的任何硒酸盐或草酸盐生长的细胞的膜组分。差异光谱，但是，揭示了存在的细胞色素b554（在554，523，和422 nm处的吸收最大值）的膜组分从硒酸盐生长的细胞和细胞色素b556（在556，520，和416 nm处的吸收最大值）的膜组分从硒酸盐生长的细胞。在不同的膜组分中的还原酶活性的分析显示底物特异性的变化。然而，酶活性对于细胞在其上生长的底物是最大的（例如，来自硝酸盐生长的细胞的膜对硝酸盐表现出最大的活性）。这些结果表明，蛋白质组成，细胞色素含量和还原酶活性取决于用于生长的末端电子受体。
Abstract The protein composition, cytochrome content, and reductase activity in the dissimilatory selenate-reducing bacterium Geospirillum barnesii strain SeS3, grown with thiosulfate, nitrate, selenate, or fumarate as the terminal electron acceptor, was investigated. Comparison of seven high-molecular-mass membrane proteins (105.3, 90.3, 82.6, 70.2, 67.4, 61.1, and 57.3 kDa) by SDS-PAGE showed that their detection was dependent on the terminal electron acceptor used. Membrane fractions from cells grown on thiosulfate contained a 70.2-kDa c-type cytochrome with absorbance maxima at 552, 522, and 421 nm. A 61.1-kDa c-type cytochrome with absorption maxima at 552, 523, and 423 nm was seen in membrane fractions from cells grown on nitrate. No c-type cytochromes were detected in membrane fractions of either selenate- or fumarate-grown cells. Difference spectra, however, revealed the presence of a cytochrome b554 (absorption maxima at 554, 523, and 422 nm) in membrane fractions from selenate-grown cells and a cytochrome b556 (absorption maxima at 556, 520, and 416 nm) in membrane fractions from fumarate-grown cells. Analysis of reductase activity in the different membrane fractions showed variability in substrate specificity. However, enzyme activity was greatest for the substrate on which the cells had been grown (e.g., membranes from nitrate-grown cells exhibited the greatest activity with nitrate). These results show that protein composition, cytochrome content, and reductase activity are dependent on the terminal electron acceptor used for growth.