GROWTH REPRESSION OF YEAST AND FUNGUS BY BACTERIAL DNAS - A POSSIBLE PHYSIOLOGICAL-FUNCTION OF DNA OTHER THAN AS A CARRIAGE OF GENETIC INFORMATION

Deoxyribonucleic acid (DNA) of bacteria (Escherichia coli, Pseudomonas aeruginosa, and Bacillus subtilis) repressed the growth of yeasts (Sa ccharomyces cerevisiae, Hansenula anomala, and Schizosaccharomyces pom be) and a fungus (Aspergillus niger), whereas the DNA of S. cerevisiae did not significantly repress the growth of bacteria. Chemically synt hesized single-stranded oligonucleotides with the CpG dinucleotide mot if also repressed the growth of S. cerevisiae. The effect of E. coli D NA was partially abolished after complete depolymerization or methylat ion of the DNA, and that of the oligonucleotides with the CpG motif de creased when the cytosine in the motif was methylated. The observed re pression of eukaryotic microbial growth by bacterial DNA is thought to be due to the presence of the CpG motif. The results indicate that DN As have some physiological function in addition to being carriers of g enetic information.