0 avis
Flexible-to-rigid transition is central for substrate transport in the ABC transporter BmrA from Bacillus subtilis
Archive ouverte
Edité par CCSD ; Nature Publishing Group -
International audience. ATP-binding-cassette (ABC) transporters are molecular pumps that translocate molecules across the cell membrane by switching between inward-facing and outward-facing states. To obtain a detailed understanding of their mechanism remains a challenge to structural biology, as these proteins are notoriously difficult to study at the molecular level in their active, membrane-inserted form. Here we use solid-state NMR to investigate the multidrug ABC transporter BmrA reconstituted in lipids. We identify the chemical-shift differences between the inward-facing, and outward-facing state induced by ATP:Mg 2+ :Vi addition. Analysis of an X-loop mutant, for which we show that ATPase and transport activities are uncoupled, reveals an incomplete transition to the outward-facing state upon ATP:Mg 2+ :Vi addition, notably lacking the decrease in dynamics of a defined set of residues observed in wild-type BmrA. This suggests that this stiffening is required for an efficient transmission of the conformational changes to allow proper transport of substrate by the pump.
Consulter en ligne
Suggestions
Du même auteur
