Bacteria Use Protein as Template to Make DNA Without RNA
Scientists studying E. coli’s defense system DRT3 found that the enzyme DRT3b can synthesize a repeating C-A-C-A DNA strand using amino acids in the enzyme as a template, effectively translating protein sequence into DNA without an RNA template, while DRT3a still makes DNA from RNA. The two strands form a double helix and together act as an antiviral defense, with RecBCD normally destroying such DNA; when RecBCD is disabled by viruses, accumulating DRT3 DNA halts bacterial growth to stop the virus. The finding, supported by cryo-EM structures and mutational tests, suggests this amino-acid–templating mechanism may be more widespread in nature.