Catalytic activity of MsbA reconstituted in nanodisc particles is modulated by remote interactions with the bilayer.
ATP-binding cassette (ABC) transporters couple hydrolysis of ATP with vectorial transport across the cell membrane. We have reconstituted ABC transporter MsbA in nanodiscs of various sizes and lipid compositions to test whether ATPase activity is modulated by the properties of the bilayer. ATP hydrolysis rates, Michaelis-Menten parameters, and dissociation constants of substrate analog ATP-γ-S demonstrated that physicochemical properties of the bilayer modulated binding and ATPase activity. This is remarkable when considering that the catalytic unit is located ~50Å from the transmembrane region. Our results validated the use of nanodiscs as an effective tool to reconstitute MsbA in an active catalytic state, and highlighted the close relationship between otherwise distant transmembrane and ATPase modules.
Department of Medical Genome Sciences, Graduate School of Frontier Sciences, The University of Tokyo, Kashiwa, Japan.
Takeaki
T
Kawai
Jose M M
JM
Caaveiro
Ryota
R
Abe
Toyomasa
T
Katagiri
Kouhei
K
Tsumoto
D018528:ATP-Binding Cassette Transporters / Q000737:chemistry*; D000251:Adenosine Triphosphatases / Q000737:chemistry; D001426:Bacterial Proteins / Q000737:chemistry*; D001665:Binding Sites; D002384:Catalysis; D006868:Hydrolysis; D007700:Kinetics; D008051:Lipid Bilayers / Q000737:chemistry*; D008954:Models, Biological
D018528:ATP-Binding Cassette Transporters; D001426:Bacterial Proteins; D008051:Lipid Bilayers; C079726:MsbA protein, Bacteria; D000251:Adenosine Triphosphatases