Conformational dynamics of the nucleotide binding domains and the power stroke of a heterodimeric ABC transporter.
Multidrug ATP binding cassette (ABC) exporters are ubiquitous ABC transporters that extrude cytotoxic molecules across cell membranes. Despite recent progress in structure determination of these transporters, the conformational motion that transduces the energy of ATP hydrolysis to the work of substrate translocation remains undefined. Here, we have investigated the conformational cycle of BmrCD, a representative of the heterodimer family of ABC exporters that have an intrinsically impaired nucleotide binding site. We measured distances between pairs of spin labels monitoring the movement of the nucleotide binding (NBD) and transmembrane domains (TMD). The results expose previously unobserved structural intermediates of the NBDs arising from asymmetric configuration of catalytically inequivalent nucleotide binding sites. The two-state transition of the TMD, from an inward- to an outward-facing conformation, is driven exclusively by ATP hydrolysis. These findings provide direct evidence of divergence in the mechanism of ABC exporters.DOI: http://dx.doi.org/10.7554/eLife.02740.001.
Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, United States.
Smriti
S
Mishra
Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, United States.
Brandy
B
Verhalen
Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, United States.
Richard A
RA
Stein
Department of Biochemistry, College of Medicine, University of Illinois, Urbana, United States Center for Biophysics and Computational Biology, University of Illinois, Urbana, United States The Beckman Institute for Advanced Science and Technology, University of Illinois, Urbana, Unites States.
Po-Chao
PC
Wen
Department of Biochemistry, College of Medicine, University of Illinois, Urbana, United States Center for Biophysics and Computational Biology, University of Illinois, Urbana, United States The Beckman Institute for Advanced Science and Technology, University of Illinois, Urbana, Unites States.
Emad
E
Tajkhorshid
Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, United States hassane.mchaourab@vanderbilt.edu.
Hassane S
HS
Mchaourab
D018528:ATP-Binding Cassette Transporters / Q000235:genetics* / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000737:chemistry / Q000235:genetics; D002352:Carrier Proteins / Q000737:chemistry / Q000235:genetics; D020134:Catalytic Domain; D002462:Cell Membrane / Q000737:chemistry; D003001:Cloning, Molecular; D005786:Gene Expression Regulation; D006868:Hydrolysis; D056004:Molecular Dynamics Simulation; D036103:Nanotechnology; D009711:Nucleotides / Q000737:chemistry / Q000235:genetics; D011487:Protein Conformation; D055503:Protein Multimerization
D018528:ATP-Binding Cassette Transporters; D002352:Carrier Proteins; D009711:Nucleotides; D000255:Adenosine Triphosphate
ABC heterodimers; ABC transporters; double electron electron resonance (DEER)