Crystal structure and site-directed mutagenesis of a bleomycin resistance protein and their significance for drug sequestering

P. Dumas (1) , M. Bergdoll (2) , Christine Cagnon (3) , J.-M. Masson

1 LURE - Laboratoire pour l'utilisation du rayonnement électromagnétique
2 IBMP - Institut de Biologie Moléculaire des Plantes
3 IPREM - Institut pluridisciplinaire de recherche sur l'environnement et les matériaux

The antibiotic bleomycin, a strong DNA cutting agent, is naturally produced by actinomycetes which have developed a resistance mechanism against such a lethal compound. The crystal structure, at 2.3 Å resolution, of a bleomycin resistance protein of 14 kDa reveals a structure in two halves with the same α/β fold despite no sequence similarity. The crystal packing shows compact dimers with a hydrophobic interface and involved in mutual chain exchange. Two independent solution studies (analytical centrifugation and light scattering) showed that this dimeric form is not a packing artefact but is indeed the functional one. Furthermore, light scattering also showed that one dimer binds two antibiotic molecules as expected. A crevice located at the dimer interface, as well as the results of a site-directed mutagenesis study, led to a model wherein two bleomycin molecules are completely sequestered by one dimer. This provides a novel insight into antibiotic resistance due to drug sequestering, and probably also into drug transport and excretion.

Domaines: Ecologie, Environnement

P. Dumas, M. Bergdoll, Christine Cagnon, J.-M. Masson. Crystal structure and site-directed mutagenesis of a bleomycin resistance protein and their significance for drug sequestering. EMBO Journal, 1994, 13 (11), pp.2483-2492. ⟨hal-01631819⟩