Proton motive force mediates a reorientation of the cytosolic domains of the multidrug transporter LmrP.
LmrP from Lactococcus lactis is a 45-kDa membrane protein that confers resistance to a wide variety of lipophilic compounds by acting as a proton motive force-driven efflux pump. This study shows that both the proton motive force and ligand interaction alter the accessibility of cytosolic tryptophan residues to a hydrophilic quencher. The proton motive force mediates an increase of LmrP accessibility toward the external medium and results in higher drug binding. Residues Asp128 and Asp68, from cytosolic loops, are involved in the proton motive force-mediated accessibility change. Ligand binding does not modify the protein accessibility, but the proton motive force-mediated restructuring is prerequisite for a subsequent accessibility change mediated by ligand binding. Asp142 cooperates with other membrane-embedded carboxylic residues to promote a conformational change that increases LmrP accessibility toward the hydrophilic quencher. This drug binding-mediated reorganization may be related to the transition between the high- and low-affinity drug-binding sites and is crucial for drug release in the extracellular medium.
Gbaguidi
B
B
Laboratory for the Structure and Function of Biological Membranes, Structural Biology and Bioinformatics Center, Free University of Brussels, CP206/2, Bd du Triomphe, 1050, Brussels, Belgium.
Mazurkiewicz
P
P
Konings
W N
WN
Driessen
A J M
AJ
Ruysschaert
J M
JM
Vigano
C
C
D020106:Acrylamide / Q000494:pharmacology; D001224:Aspartic Acid / Q000737:chemistry; D001426:Bacterial Proteins / Q000737:chemistry / Q000502:physiology*; D001562:Benzimidazoles / Q000494:pharmacology; D001692:Biological Transport; D002462:Cell Membrane / Q000378:metabolism; D003600:Cytosol / Q000737:chemistry; D004305:Dose-Response Relationship, Drug; D018432:Drug Resistance, Multiple; D006863:Hydrogen-Ion Concentration; D013294:Lactococcus lactis / Q000378:metabolism; D008024:Ligands; D008081:Liposomes / Q000378:metabolism; D026901:Membrane Transport Proteins / Q000737:chemistry / Q000502:physiology*; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D011510:Proteolipids / Q000737:chemistry; D011522:Protons; D012685:Sepharose / Q000737:chemistry; D017550:Spectroscopy, Fourier Transform Infrared; D013752:Tetracycline / Q000737:chemistry; D013997:Time Factors; D014364:Tryptophan / Q000737:chemistry
D001426:Bacterial Proteins; D001562:Benzimidazoles; D008024:Ligands; D008081:Liposomes; C096807:LmrP protein, Lactococcus lactis; D026901:Membrane Transport Proteins; D011510:Proteolipids; D011522:Protons; C020485:proteoliposomes; D020106:Acrylamide; D001224:Aspartic Acid; D014364:Tryptophan; D012685:Sepharose; D013752:Tetracycline; C017807:bisbenzimide ethoxide trihydrochloride