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 5'-deoxyadenosylcobalamine (coenzyme B12). Genetic information processing; DNA replication. A member of the dormancy regulon. Induced in response to reduced oxygen tension (hypoxia), low levels of nitric oxide (NO) and carbon monoxide (CO). It is hoped that this regulon will give insight into the latent, or dormant phase of infection. No visible phenotype, even under low-oxygen growth conditions, nor in aerosol-infected B6D2/F1 mice. Was identified as a high-confidence drug target. Belongs to the ribonucleoside diphosphate reductase class-2 family. Truncated N-terminus.