A new experimental approach to detect long-range conformational changes transmitted between the membrane and cytosolic domains of LmrA, a bacterial multidrug transporter.
LmrA confers multidrug resistance to Lactococcus lactis by mediating the extrusion of antibiotics, out of the bacterial membrane, using the energy derived from ATP hydrolysis. Cooperation between the cytosolic and membrane-embedded domains plays a crucial role in regulating the transport ATPase cycle of this protein. In order to demonstrate the existence of a structural coupling required for the cross-talk between drug transport and ATP hydrolysis, we studied specifically the dynamic changes occurring in the membrane-embedded and cytosolic domains of LmrA by combining infrared linear dichroic spectrum measurements in the course of H/D exchange with Trp fluorescence quenching by a water-soluble attenuator. This new experimental approach, which is of general interest in the study of membrane proteins, detects long-range conformational changes, transmitted between the membrane-embedded and cytosolic regions of LmrA. On the one hand, nucleotide binding and hydrolysis in the cytosolic nucleotide binding domain cause a repacking of the transmembrane helices. On the other hand, drug binding to the transmembrane helices affects both the structure of the cytosolic regions and the ATPase activity of the nucleotide binding domain.
Vigano
Catherine
C
Service de Structure et Fonction des Membranes Biologiques (SFMB), Université Libre de Bruxelles, P.O. Box 206/2, Bd du Triomphe, B1050 Brussels, Belgium. cvigano@ulb.ac.be
Grimard
Vinciane
V
Margolles
Abelardo
A
Goormaghtigh
Erik
E
van Veen
Hendrik W
HW
Konings
Wil N
WN
Ruysschaert
Jean Marie
JM
D000255:Adenosine Triphosphate / Q000378:metabolism; D001426:Bacterial Proteins / Q000737:chemistry / Q000378:metabolism*; D002384:Catalysis; D002462:Cell Membrane; D003600:Cytosol / Q000378:metabolism; D004352:Drug Resistance, Microbial; D006868:Hydrolysis; D013294:Lactococcus lactis / Q000187:drug effects / Q000378:metabolism; D027425:ATP-Binding Cassette, Sub-Family C Proteins / Q000737:chemistry / Q000378:metabolism*; D011487:Protein Conformation; D017550:Spectroscopy, Fourier Transform Infrared
D000255:Adenosine Triphosphate; D001426:Bacterial Proteins; D027425:ATP-Binding Cassette, Sub-Family C Proteins; C101824:LmrA protein, Lactococcus lactis