Fig. 1

ABC transporter export cycle and samples studied. a Putative export cycle of an ABC exporter adapted from Grossmann et al.²⁶ and Parcej et al.²⁷. A sketched model of the BmrA homodimer is given in gray, ATP is indicated in red, and ADP in yellow. Bound nucleotides in undetermined hydrolysis states are shown in gray. b Mimics of different BmrA states investigated, as desribed in the text. c BmrA homology model based on Sav1866 (pdb 2hyd²), the two mononers are shown in light gray and dark gray colors. Mutated residues are highligthed, with E474 from the X-loop motif (470-TEVGERG-476) in green, residue K380 from the Walker A motif (374-GPSGGKT-381) in magenta, and residue E504 from Walker B (496-ILMLDE-504) in dark yellow. The ABC signature (477-LSGGQ-483, in blue) and the H-loop (532-AHR-536, in cyan) motifs are also presented. d View of the NBDs of BmrA modeled on Sav1866 (pdb 2hyd²). A362, A371, A505, and A534 (as discussed in the text) are shown in black spheres, with the Mg²⁺ ions represented in light green sphere