Membrane insertion stabilizes the structure of TrwB, the R388 conjugative plasmid coupling protein

► The α-helical component of TrwB remains unchanged when inserted into the bilayer. ► Incorporation of TrwB into lipid bilayers causes an increase in β-strand structures. ► β-strand structures are probably related to protein-protein contacts in the bilayer. ► TrwB adopts a more stable conformation when reconstituted into liposomes. ► Incorporation of TrwB into lipid bilayers causes an increase in lipid chain order.