Abstract
Pdr5, a member of the extensive ABC transporter superfamily, is representative of a clinically relevant subgroup involved in pleiotropic drug resistance. Pdr5 and its homologues drive drug efflux through uncoupled hydrolysis of nucleotides, enabling organisms such as baker’s yeast and pathogenic fungi to survive in the presence of chemically diverse antifungal agents. Here, we present the molecular structure of Pdr5 solved with single particle cryo-EM, revealing details of an ATP-driven conformational cycle, which mechanically drives drug translocation through an amphipathic channel, and a clamping switch within a conserved linker loop that acts as a nucleotide sensor. One half of the transporter remains nearly invariant throughout the cycle, while its partner undergoes changes that are transmitted across inter-domain interfaces to support a peristaltic motion of the pumped molecule. The efflux model proposed here rationalises the pleiotropic impact of Pdr5 and opens new avenues for the development of effective antifungal compounds.
Highlights
Pdr[5], a member of the extensive ATP-binding cassette (ABC) transporter superfamily, is representative of a clinically relevant subgroup involved in pleiotropic drug resistance
Compared to the detergent-solubilised state, the kinetic parameter Vmax (72.8 ± 2.9 nmol min−1 mg−1) decreased 3-fold and KM (0.65 ± 0.01 mM) increased 1.5-fold One possible explanation is that the peptidisc belt, more rigid than the detergent shell, interfered with the efficiency of ATP hydrolysis
This preparation yielded homogenous particles readily visualised by electron cryo-microscopy (Supplementary Fig. 2a, b)
Summary
Pdr[5], a member of the extensive ABC transporter superfamily, is representative of a clinically relevant subgroup involved in pleiotropic drug resistance. The sample with added ATP and R6G produced a map with the nucleotide composition as above, and with a bound substrate in the transport cavity, called here R6G-Pdr[5] (Supplementary Fig. 3i).
Sign-in/Register to view highlights & summary 
Published Version (
Free)
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call