Reverse transcriptase (RT) component of antiviral defense system retron Ec67, minimally composed of a non-coding RNA (ncRNA) and this RT. Expression of these 2 elements confers protection against bacteriophage T5. At multiplicity of infection (MOI) of 0.02 cultures grow normally when infected with T5 without collapsing, at MOI 2 cultures enter growth stasis (PubMed:33157039). Responsible for synthesis of msDNA-Ec67 (a branched molecule with RNA linked by a 2',5'-phosphodiester bond to ssDNA). The retron transcript serves as primer (from a conserved internal G residue) and template for the reaction, and codes for the RT (PubMed:2466332, PubMed:1378431, PubMed:1692831). Can use other retrons as substrate (msDNA-Mx162 and msDNA-Ec86). Also able to synthesize DNA from a DNA template at least in vitro, although the enzyme is less active with a DNA template (PubMed:1692831). a 2'-deoxyribonucleoside 5'-triphosphate + DNA(n) = diphosphate + DNA(n+1) Endonucleolytic cleavage to 5'-phosphomonoester. The N-terminus is the reverse transcriptase, the C-terminus (downstream of residue 430) is also required for msDNA synthesis (PubMed:2466332). The C-terminus was originally suggested to have RNase H activity, but may have another nuclease activity instead (Probable). No synthesis of msDNA. Retrons may be the ancestors of retrovirus. Belongs to the bacterial reverse transcriptase family.