Provides the precursors necessary for DNA synthesis. Catalyzes the biosynthesis of deoxyribonucleotides from the corresponding ribonucleotides. When coexpressed in E.coli with nrdF2 the 2 proteins complement a temperature-sensitive E.coli mutant, however coexpression with nrdF1 does not complement. [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). CDP reduction is stimulated by dATP. Genetic information processing; DNA replication. Tetramer of two alpha and two beta subunits (Probable). Co-immunoprecipitates with DarG in the presence and absence of darT (PubMed:32634279). Initially decreases as oxygen levels drop, then rises again. Belongs to the ribonucleoside diphosphate reductase large chain family. Truncated N-terminus.