| Abstract
| - OmpG, a porin from E. coli, has been examined in planar lipid bilayers and in detergentsolution. First, bilayer recordings were used to reinforce the evidence that the functional form of OmpGis a monomer. Both pH-dependent gating and blockade by covalent modification add support to thisproposal. The findings contrast with the properties of the classical porins, which function as trimers.Second, the folding of OmpG in detergent solution was examined. A water-soluble form of OmpG wasobtained by dialysis from denaturant into buffer. Incubation of water-soluble OmpG in detergent resultsin conversion to a form that possesses the hallmarks of a β barrel. The folding of water-soluble OmpGin detergent was monitored by circular dichroism, protease resistance, and heat modifiability. OmpG isfirst transformed into an intermediate with increased β-sheet content on the time scale of minutes at 23°C. This is followed by the slow acquisition of heat modifiability and protease resistance over severalhours. The formation of a β barrel during this period was demonstrated in a double cysteine mutant byusing intramolecular disulfide bond formation to report N and C terminus proximity. Finally, conditionsare presented for folding OmpG with greater than 90% efficiency, thereby paving the way for structuralstudies.
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