A single active catalytic site is sufficient to promote transport in P-glycoprotein

Bársony, orsolya and Szalóki, Gábor and Türk, Dóra and Tarapcsák, Szabolcs and Gutay-Tóth, Zsuzsanna and Bacsó, Zsolt and Székvölgyi, Lóránt and Szabó, Gábor and Csanády, László and Szakács, Gergely and Kormosné Goda, Katalin (2016) A single active catalytic site is sufficient to promote transport in P-glycoprotein. SCIENTIFIC REPORTS, 6 (24810). pp. 1-16. ISSN 2045-2322

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Abstract

P-glycoprotein (Pgp) is an ABC transporter responsible for the ATP-dependent efflux of chemotherapeutic compounds from multidrug resistant cancer cells. Better understanding of the molecular mechanism of Pgp-mediated transport could promote rational drug design to circumvent multidrug resistance. By measuring drug binding affinity and reactivity to a conformation-sensitive antibody we show here that nucleotide binding drives Pgp from a high to a low substrate-affinity state and this switch coincides with the flip from the inward- to the outward-facing conformation. Furthermore, the outward-facing conformation survives ATP hydrolysis: the post-hydrolytic complex is stabilized by vanadate, and the slow recovery from this state requires two functional catalytic sites. The catalytically inactive double Walker A mutant is stabilized in a high substrate affinity inward-open conformation, but mutants with one intact catalytic center preserve their ability to hydrolyze ATP and to promote drug transport, suggesting that the two catalytic sites are randomly recruited for ATP hydrolysis.

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