A new species of multicopy single-stranded DNA from Myxococcus xanthus with conserved structural features

Myxobacteria have been shown to contain a large number of branched RNA-linked single-stranded DNA (multicopy single-stranded DNA (msDNA)) molecules. In addition, we found that Myxococcus xanthus contain another smaller msDNA-like molecule, designated mrDNA, consisting of a 65-base single-stranded DNA covalently linked by a 2',5'-phosphodiester linkage to a 49-base branched RNA. In spite of their different primary sequences, the RNA-linked mrDNA is remarkably similar in secondary structure to msDNA, sharing similar stem-loop folding as well as the unique 2',5'-phosphodiester linkage. These results indicate that these novel molecules are synthesized by common molecular mechanisms.