Provides the precursors necessary for DNA synthesis. Catalyzes the biosynthesis of deoxyribonucleotides from the corresponding ribonucleotides (By similarity). [thioredoxin]-disulfide + a 2'-deoxyribonucleoside 5'-diphosphate + H2O = [thioredoxin]-dithiol + a ribonucleoside 5'-diphosphate Under complex allosteric control mediated by deoxynucleoside triphosphates and ATP binding. The type of nucleotide bound at the specificity site determines substrate preference. It seems probable that ATP makes the enzyme reduce CDP and UDP, dGTP favors ADP reduction and dTTP favors GDP reduction (By similarity). Genetic information processing; DNA replication. Tetramer of two alpha and two beta subunits. Pupylation of this protein has been demonstrated, although it is unknown if the protein concerned is the product of this gene, of the identical gene MSMEG_1019 (AC P0CG99), or of both genes. Belongs to the ribonucleoside diphosphate reductase large chain family. Truncated N-terminus.