title: DNA-supercoiling is affected in vitro by the peptide antibiotics tyrocidine and gramicidin.
abstract: Tyrocidine, a peptide antibiotic produced by Bacillus brevis (ATCC 8185), relaxes superhelical DNA in a biphasic manner and induces 'packaging' of the DNA at higher concentrations. This was concluded from studies using the sensitive 4,5',8-trimethylpsoralen photobinding technique [Sinden, R. R., Carlson, J. O. & Pettijohn, D.-E. (1980) Cell 21, 773-783]. Relaxed DNA is not affected by tyrocidine whereas linearized molecules become packaged. The linear gramicidin synthesized by the same strain reverses the tyrocidine-induced relaxation as well as the packaging, an observation which might be of biological relevance.
mesh_terms: D004278:DNA, Superhelical / Q000187:drug effects* / Q000528:radiation effects; D004926:Escherichia coli / Q000235:genetics; D011564:Furocoumarins; D006096:Gramicidin / Q000494:pharmacology*; D010957:Plasmids; D014440:Tyrocidine / Q000494:pharmacology*; D014449:Tyrothricin / Q000494:pharmacology*; D014466:Ultraviolet Rays
chemical_list: D004278:DNA, Superhelical; D011564:Furocoumarins; D014440:Tyrocidine; D014449:Tyrothricin; D006096:Gramicidin