Reverse transcriptase (RT) responsible for synthesis of msDNA-Mx65 (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 (By similarity). The retron is involved in antiviral defense (By similarity). a 2'-deoxyribonucleoside 5'-triphosphate + DNA(n) = diphosphate + DNA(n+1) M.xanthus contains two independent and unlinked retrons: Mx65 and Mx162. Retrons may be the ancestors of retrovirus. Belongs to the bacterial reverse transcriptase family.