Mechanism of inhibition of DNA gyrase by cyclothialidine, a novel DNA gyrase inhibitor.
We investigated how cyclothialidine (Ro 09-1437), a novel DNA gyrase inhibitor belonging to a new chemical class of compounds, acts to inhibit Escherichia coli DNA gyrase. Cyclothialidine up to 100 micrograms/ml showed no effect on DNA gyrase when linear DNA was used as a substrate. Under the same conditions, quinolones, which inhibit the resealing reaction of DNA gyrase, caused a decrease in the amount of linear DNA used. No effect of cyclothialidine was observed on the accumulation of the covalent complex of DNA and the A subunit of DNA gyrase induced by ofloxacin in the absence of ATP. The effect of cyclothialidine on the DNA supercoiling reaction was antagonized by ATP, reducing the inhibitory activity 11-fold as the ATP concentration was increased from 0.5 to 5 mM. Cyclothialidine competitively inhibited the ATPase activity of DNA gyrase (Ki = 6 nM). The binding of [14C]benzoyl-cyclothialidine to E. coli gyrase was inhibited by ATP and novobiocin, but not by ofloxacin. These results suggest that cyclothialidine acts by interfering with the ATPase activity of the B subunit of DNA gyrase. Cyclothialidine was active against a DNA gyrase resistant to novobiocin, suggesting that its precise site of action might be different from that of novobiocin.
Nakada
N
N
Nippon Roche Research Center, Kamakura, Japan.
Gmünder
H
H
Hirata
T
T
Arisawa
M
M
D042462:4-Quinolones; D000251:Adenosine Triphosphatases / Q000037:antagonists & inhibitors; D000255:Adenosine Triphosphate / Q000378:metabolism / Q000494:pharmacology; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D000890:Anti-Infective Agents / Q000494:pharmacology; D001667:Binding, Competitive; D002250:Carbon Radioisotopes; D003374:Coumarins / Q000494:pharmacology; D004250:DNA Topoisomerases, Type II / Q000235:genetics / Q000378:metabolism; D004269:DNA, Bacterial / Q000187:drug effects / Q000378:metabolism; D004278:DNA, Superhelical / Q000187:drug effects / Q000378:metabolism; D004926:Escherichia coli / Q000201:enzymology / Q000235:genetics; D009154:Mutation; D010456:Peptides, Cyclic / Q000037:antagonists & inhibitors / Q000378:metabolism / Q000494:pharmacology*; D059005:Topoisomerase II Inhibitors
D042462:4-Quinolones; D000900:Anti-Bacterial Agents; D000890:Anti-Infective Agents; D002250:Carbon Radioisotopes; D003374:Coumarins; D004269:DNA, Bacterial; D004278:DNA, Superhelical; D010456:Peptides, Cyclic; D059005:Topoisomerase II Inhibitors; C091204:benzoylcyclothialidine; C085889:cyclothialidine; D000255:Adenosine Triphosphate; D000251:Adenosine Triphosphatases; D004250:DNA Topoisomerases, Type II