大肠杆菌对亚硒酸盐的选择性同化作用。

Selective assimilation of selenite by Escherichia coli.

作者信息

Brown T A, Shrift A

出版信息

Can J Microbiol. 1982 Mar;28(3):307-10. doi: 10.1139/m82-045.

Abstract

The assimilation of selenite by Escherichia coli involves a transport process specific for this anion. Cystine, a repressor of sulfate and selenite uptake, when added to the growth medium, had no effect on selenite uptake; nor did sulfite inhibit assimilation of selenite. Cells grown aerobically in a basic salts medium transported selenite at an initial rate of 0.14 mumol . g-1 min-1 and a Vmax of 393.0 mumol. g-1 . min-1. In contrast, cells grown in a medium that contained the trace elements necessary for synthesis of the selenoenzyme formate dehydrogenase took up selenite at a significantly faster rate (initial rate = 0.27 mumol . g-1 . min-1, Vmax = 658.2 mumol . g-1 . min-1). Km values for the transport process in the two media, however, were found to be similar. The results suggest the existence of a metabolic pathway, specific for selenite, responsible for the incorporation of selenium into formate dehydrogenase.U

摘要

大肠杆菌对亚硒酸盐的同化作用涉及一种针对该阴离子的转运过程。胱氨酸是硫酸盐和亚硒酸盐摄取的抑制剂，当添加到生长培养基中时，对亚硒酸盐的摄取没有影响；亚硫酸盐也不抑制亚硒酸盐的同化作用。在碱性盐培养基中需氧生长的细胞以0.14 μmol·g⁻¹·min⁻¹的初始速率和393.0 μmol·g⁻¹·min⁻¹的Vmax转运亚硒酸盐。相比之下，在含有合成硒酶甲酸脱氢酶所需微量元素的培养基中生长的细胞摄取亚硒酸盐的速度明显更快（初始速率 = 0.27 μmol·g⁻¹·min⁻¹，Vmax = 658.2 μmol·g⁻¹·min⁻¹）。然而，发现两种培养基中转运过程的Km值相似。结果表明存在一条特定于亚硒酸盐的代谢途径，负责将硒掺入甲酸脱氢酶中。