The maltose ABC transporter: action of membrane lipids on the transporter stability, coupling and ATPase activity.

Huan Bao, Kush Dalal, Victor Wang, Isabelle Rouiller, Franck Duong

Department of Biochemistry & Molecular Biology, University of British Columbia, Vancouver, Canada.

Biochimica et biophysica acta 2013 Aug

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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. Copyright © 2013 Elsevier B.V. All rights reserved.

Citation

Huan Bao, Kush Dalal, Victor Wang, Isabelle Rouiller, Franck Duong. The maltose ABC transporter: action of membrane lipids on the transporter stability, coupling and ATPase activity. Biochimica et biophysica acta. 2013 Aug;1828(8):1723-30