Retron

A retron is a distinct DNA sequence found in the genome of many bacteria species that codes for reverse transcriptase and a unique single-stranded DNA/RNA hybrid called multicopy single-stranded DNA (msDNA). Retron msr RNA is the non-coding RNA produced by retron elements and is the immediate precursor to the synthesis of msDNA. The retron msr RNA folds into a characteristic secondary structure that contains a conserved guanosine residue at the end of a stem loop. Synthesis of DNA by the retron-encoded reverse transcriptase (RT) results in a DNA/RNA chimera which is composed of small single-stranded DNA linked to small single-stranded RNA. The RNA strand is joined to the 5′ end of the DNA chain via a 2′–5′ phosphodiester linkage that occurs from the 2′ position of the conserved internal guanosine residue.