Intrastrand self-complementary sequences in Bacillus subtilis DNA

Intrastrand self-complementary sequences have been isolated from the DNA of Bacillus subtilis by hydroxyapatite (HA) chromatography following thermal renaturation of strands separated by chromatography on methylated albumin kieselguhr (MAK). The instrastrand structures derived from the MAK H strand (HA HII) were biologically active showing transforming activity for a wide variety of markers, as well as hybridization to both pulse-labelled and ribosomal RNA. Removal of regions of single-strand DNA with S1 nuclease did not significantly alter the biological activity of the self-annealed molecules. The overall efficiency of transformation and hybridization of the intrastrand self-annealing DNA was low suggesting that many sequences in the population are neither active in transformation to prototrophy nor transcribed into RNA.