Wiley, FEBS Letters, 18(587), p. 2984-2988, 2013
DOI: 10.1016/j.febslet.2013.06.056
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Periplasmic adaptor proteins are essential components of bacterial tripartite multidrug efflux pumps. Here we report the 2.35Å resolution crystal structure of the BesA adaptor from the spirochete Borrelia burgdorferi solved using selenomethionine derivatized protein. BesA shows the archetypal linear, flexible, multi-domain architecture evident among proteobacteria and retains the lipoyl, β-barrel and membrane-proximal domains that interact with the periplasmic domains of the inner membrane transporter. However, it lacks the α-hairpin domain shown to establish extensive coiled-coil interactions with the periplasmic entrance helices of the outer membrane-anchored TolC exit duct. This has implications for the modelling of assembled tripartite efflux pumps.