FIGURE 4.
Proposed model for PulD assembly in lecithin liposomes. Rapid monomer association with the liposomes leads to membrane-bound oligomerization (i) into a prepore structure (ii) that inserts (iii) upon the activation of a conformational switch to achieve the trypsin-resistant native state. The acquisition of native state determinants at each stage is also shown. The asterisk indicates the likely immature PulD multimer that can be isolated on non-fluid diC16:0PC liposomes. Note that SDS and urea resistance are not obtained in diC16:0PC liposomes, which likely prevent essential membrane-embedded interactions to achieve such a resistance.