The MacA–MacB–TolC tripartite complex is a transmembrane machine that spans both plasma membrane and outer membrane and actively extrudes substrates, including macrolide antibiotics, virulence factors, peptides and cell envelope precursors. These transport activities are driven by the ATPase MacB, a member of the ATP-Binding Cassette (ABC) superfamily. Here, we present the crystal structure of MacB at 3.4 Å resolution. MacB forms a dimer in which each protomer contains a nucleotide binding domain and four transmembrane helices that protrude in the periplasm into a binding domain for interaction with the membrane fusion protein MacA. MacB represents an ABC transporter in pathogenic microorganisms with unique structural features.

The data sets included in this repository concern results of cell growth experiments in Fig. 1b and Table 2, and the raw immuno blot data for Supplementary Figure 14.