Interaction of epothilone B (patupilone) with microtubules as detected by two-domesional Solid-state NMR

Microtubule ligands such as taxanes and epothilones have emerged as broadly applied chemotherapeutic agents. Epothilones are known to induce the polymerization of ab-tubulin dimers into microtubules leading to apoptosis of cancer cells. It appears that epothilone B (patupilone) is more potent cytotoxic agent against multi-resistant tumor cells than epothilone A and taxanes. These observations invoke a strong interest in understanding the functional mechanism for the interaction of patupilone with a,b-tubulin to deduce an optimized anticancer drug. The recent electron crystallography studies on Epothilone A bound to a,b-tubulin in zinc-stabilized sheets and solution NMR studies of epothilone A in equilibrium with a,b-tubulin heterodimers lead to controversial binding models. Here, we have used solid-state NMR techniques with the aim to understand the binding mode of patupilone to intact microtubules. We obtained high resolution ssNMR spectra of patupilone bound to microtubules and identified atomic positions of the drug that undergo clear changes of chemical shift upon binding