Structural basis for lipid and copper regulation of the ABC transporter MsbA. Academic Article uri icon


  • A critical step in lipopolysaccharide (LPS) biogenesis involves flipping lipooligosaccharide, an LPS precursor, from the cytoplasmic to the periplasmic leaflet of the inner membrane, an operation carried out by the ATP-binding cassette transporter MsbA. Although LPS binding to the inner cavity of MsbA is well established, the selectivity of MsbA-lipid interactions at other site(s) remains poorly understood. Here we use native mass spectrometry (MS) to characterize MsbA-lipid interactions and guide structural studies. We show the transporter co-purifies with copper(II) and metal binding modulates protein-lipid interactions. A 2.15 resolution structure of an N-terminal region of MsbA in complex with copper(II) is presented, revealing a structure reminiscent of the GHK peptide, a high-affinity copper(II) chelator. Our results demonstrate conformation-dependent lipid binding affinities, particularly for the LPS-precursor, 3-deoxy-D-manno-oct-2-ulosonic acid (Kdo)2-lipid A (KDL). We report a 3.6-resolution structure of MsbA trapped in an open, outward-facing conformation with adenosine 5'-diphosphate and vanadate, revealing a distinct KDL binding site, wherein the lipid forms extensive interactions with the transporter. Additional studies provide evidence that the exterior KDL binding site is conserved and a positive allosteric modulator of ATPase activity, serving as a feedforward activation mechanism to couple transporter activity with LPS biosynthesis.

published proceedings

  • Nat Commun

author list (cited authors)

  • Lyu, J., Liu, C., Zhang, T., Schrecke, S., Elam, N. P., Packianathan, C., ... Laganowsky, A.

complete list of authors

  • Lyu, Jixing||Liu, Chang||Zhang, Tianqi||Schrecke, Samantha||Elam, Nicklaus P||Packianathan, Charles||Hochberg, Georg KA||Russell, David||Zhao, Minglei||Laganowsky, Arthur

publication date

  • November 2022