DNAdependent

DNA-dependent describes enzymes or processes that require DNA as a template or substrate to function. In this usage, the activity or synthesis hinges on the presence of DNA, and the DNA sequence guides the outcome. The term is often paired with classes of polymerases or other factors that interact with DNA to carry out replication, transcription, or repair.

DNA-dependent DNA polymerases replicate DNA by copying a DNA template. They synthesize new DNA strands in a 5' to 3' direction and rely on existing DNA as a guide. In bacteria, the main replicative enzyme is DNA polymerase III, with other polymerases (such as Pol I) involved in primer removal and repair. In eukaryotes, replicative polymerases include Pol alpha, delta, and epsilon, with Pol gamma operating in mitochondria. These enzymes also participate in DNA repair pathways that require a DNA template.

DNA-dependent RNA polymerases transcribe RNA using DNA as the template. Bacterial RNA polymerase transcribes all RNA species from genomic DNA, while in eukaryotes RNA polymerase II transcribes mRNA, polymerase I synthesizes rRNA, and polymerase III synthesizes tRNA and other small RNAs. These enzymes recognize promoter regions and require transcription factors to initiate synthesis.

DNA-dependent protein kinase (DNA-PK) represents another example, activating upon binding to DNA ends during double-strand break repair via non-homologous end joining. Overall, DNA-dependent processes are central to faithful genome replication, expression, and maintenance, and are distinguished from RNA-dependent or template-independent activities.