Wetterauer B, Véron M, Miginiac-Maslow M, Decottignies P, Jacquot J P
Unité de Biochimie Cellulaire, Institut Pasteur, Paris, France.
Eur J Biochem. 1992 Oct 15;209(2):643-9. doi: 10.1111/j.1432-1033.1992.tb17331.x.
Multiple genes for thioredoxins (TRX) have been demonstrated in Dictyostelium discoideum. We expressed the cDNA for one of these genes (DdTrx1) in E. coli and purified the protein to homogeneity. The interaction with classic substrates as well as TRX reductases was analysed. It reacted with every tested substrate: insulin, NADP-dependent malate dehydrogenase and fructose-1,6-bisphosphatase. With a S0.5 of 20 microM, the reactivity with the fructose-1,6-bisphosphatase is the highest ever found for a heterologous TRX. DdTRX1 itself is accepted as a substrate by the chloroplast ferredoxin-dependent TRX reductase, as well as by the E. coli NADPH-dependent TRX reductase. Thus, the Dictyostelium TRX is functionally promiscuous. Its reactivity with insulin, chloroplast NADP-dependent malate dehydrogenase and ferredoxin-dependent TRX reductase resemble those of other TRX. It is, however, clearly different in its good interaction with chloroplast fructose-1,6-bisphosphatase and in its poor interaction with E. coli NADP-dependent TRX reductase.
在盘基网柄菌中已证实存在多个硫氧还蛋白（TRX）基因。我们在大肠杆菌中表达了其中一个基因（DdTrx1）的cDNA，并将该蛋白纯化至同质。分析了其与经典底物以及TRX还原酶的相互作用。它能与所有测试底物发生反应：胰岛素、NADP依赖性苹果酸脱氢酶和果糖-1,6-二磷酸酶。果糖-1,6-二磷酸酶的S0.5为20微摩尔，其与该酶的反应活性是迄今发现的异源TRX中最高的。DdTRX1本身可被叶绿体铁氧还蛋白依赖性TRX还原酶以及大肠杆菌NADPH依赖性TRX还原酶作为底物。因此，盘基网柄菌TRX在功能上具有多专一性。它与胰岛素、叶绿体NADP依赖性苹果酸脱氢酶和铁氧还蛋白依赖性TRX还原酶的反应活性与其他TRX相似。然而，它与叶绿体果糖-1,6-二磷酸酶的良好相互作用以及与大肠杆菌NADP依赖性TRX还原酶的不良相互作用明显不同。
