Identification of a Thioredoxin Induced by Bacteriophage T4

Abstract Infection of Escherichia coli with bacteriophage T4 was previously shown to induce the synthesis of two new proteins involved in the reduction of ribonucleoside 5'-diphosphates to deoxyribonucleoside 5'-diphosphates. One of these proteins has now been purified to homogeneity and was characterized as a thioredoxin. The other protein is a new ribonucleotide reductase. T4 thioredoxin has a molecular weight of around 10,500. It is reduced by thioredoxin reductase from uninfected E. coli. In its reduced form, T4 thioredoxin is the specific hydrogen donor of the T4-induced ribonucleotide reductase.