title: The maltose ABC transporter: action of membrane lipids on the transporter stability, coupling and ATPase activity.
abstract: The coupling between ATP hydrolysis and substrate transport remains a key question in the understanding of ABC-mediated transport. We show using the MalFGK2 complex reconstituted into nanodiscs, that membrane lipids participate directly to the coupling reaction by stabilizing the transporter in a low energy conformation. When surrounded by short acyl chain phospholipids, the transporter is unstable and hydrolyzes large amounts of ATP without inducing maltose. The presence of long acyl chain phospholipids stabilizes the conformational dynamics of the transporter, reduces its ATPase activity and restores dependence on maltose. Membrane lipids therefore play an essential allosteric function, they restrict the transporter ATPase activity to increase coupling to the substrate. In support to the notion, we show that increasing the conformational dynamics of MalFGK2 with mutations in MalF increases the transporter ATPase activity but decreases the maltose transport efficiency.
authors.affiliation: Department of Biochemistry & Molecular Biology, University of British Columbia, Vancouver, Canada.
authors.forename: Huan
authors.initials: H
authors.lastname: Bao
authors.forename: Kush
authors.initials: K
authors.lastname: Dalal
authors.forename: Victor
authors.initials: V
authors.lastname: Wang
authors.forename: Isabelle
authors.initials: I
authors.lastname: Rouiller
authors.forename: Franck
authors.initials: F
authors.lastname: Duong
mesh_terms: D018528:ATP-Binding Cassette Transporters / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D000251:Adenosine Triphosphatases / Q000378:metabolism*; D000255:Adenosine Triphosphate / Q000378:metabolism; D001692:Biological Transport; D002942:Circular Dichroism; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism*; D029968:Escherichia coli Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D008320:Maltose / Q000378:metabolism*; D008563:Membrane Lipids / Q000378:metabolism*; D009154:Mutation / Q000235:genetics; D036103:Nanotechnology; D033902:Periplasmic Binding Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D017510:Protein Folding
chemical_list: D018528:ATP-Binding Cassette Transporters; D029968:Escherichia coli Proteins; C461619:MalE protein, E coli; D008563:Membrane Lipids; D033902:Periplasmic Binding Proteins; C461599:maltose transport system, E coli; D008320:Maltose; D000255:Adenosine Triphosphate; D000251:Adenosine Triphosphatases