The interaction of coumarin antibiotics with fragments of DNA gyrase B protein.

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Gormley NA, Orphanides G, Meyer A, Cullis PM, Maxwell A

The interaction of coumarin antibiotics with fragments of DNA gyrase B protein.

Biochemistry. 1996 Apr 16;35(15):5083-92.

PubMed ID

8664301 [ View in PubMed

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Abstract

DNA gyrase is the target of the coumarin group of antibacterial agents. The drugs are known to inhibit the ATPase activity of gyrase and bind to the 24-kDa N-terminal subdomain of gyrase B protein. Supercoiling assays with intact DNA gyrase and ATPase assays with a 43-kDa N-terminal fragment of the B protein suggest that the drugs bind tightly, with Kd values <10(-7) M. In addition, the ATPase data suggest that 1 coumermycin molecule interacts with 2 molecules of the 43-kDa protein while the other coumarins form a 1:1 complex. This result is confirmed by cross-linking experiments. Rapid gel-filtration experiments show that the binding of ADPNP(5'-adneylyl beta,gamm-imidodiphosphate) and coumarins to the 43-kDa protein is mutally exclusive, consistent with a competitive mode of action for the drugs. Rapid gel-filtration binding experiments using both the 24-and 43-kDa proteins also show that the drugs bind with association rate constants of >10(5) M-1.s-1, and dissociation rate constants of approximately 3x10(-3)s-1 and approximately 4x10(-3)s-1 for the 43-and 24-kDa proteins, respectively. Titration calorimetry shows that the Kd values for coumarins binding to both proteins are approximately 10-8M and that binding is enthalpy driven.

DrugBank Data that Cites this Article

Drug Targets

Drug	Target	Kind	Organism	Pharmacological Action	Actions
Novobiocin	DNA gyrase subunit B	Protein	Staphylococcus aureus	Yes	Inhibitor	Details