A dual sensor regulates P-glycoprotein's structural plasticity.

Area of Science:

• Membrane protein structure and function
• Biochemistry and biophysics
• Drug efflux mechanisms

Background:

• P-glycoprotein (P-gp) is a crucial efflux pump with a broad substrate profile, impacting drug efficacy and resistance.
• Understanding P-gp's polyspecificity and regulation by substrate binding and lipid environment is vital for clinical applications.
• Previous structural data implicated transmembrane helices 4 and 10 in substrate recognition.

Purpose of the Study:

• To elucidate the distinct roles of transmembrane helices 4 and 10 in P-glycoprotein activity and substrate recognition.
• To investigate how the lipid environment and substrate binding modulate P-gp function.
• To decipher the structural basis for P-gp's functional plasticity.

Main Methods:

• Utilized cryogenic electron microscopy (cryo-EM) to study P-glycoprotein structure.
• Employed detergent and nanodisc systems to investigate environment- and substrate-dependent phenotypes.
• Analyzed structural data to correlate with ATPase activity and functional observations.

Main Results:

• Deciphered distinct and unexpected roles for transmembrane helices 4 and 10 in P-gp function.
• Identified helix 4 as an environment sensor and helix 10 as the primary substrate recognition element.
• Provided structural explanations for differences in P-gp's ATPase activity based on helix roles.
• Visualized the interplay between P-gp, its lipid environment, and substrates.

Conclusions:

• P-glycoprotein exhibits a dual regulation mechanism involving helix 4 (environment sensing) and helix 10 (substrate recognition).
• This dual mechanism underlies P-gp's functional plasticity and broad substrate specificity.
• The findings offer insights into the intricate interplay between membrane proteins and their lipid environments.