Outer membrane permeability: Antimicrobials and diverse nutrients bypass porins in <i>Pseudomonas aeruginosa</i>
Johanna Ude, Vishwachi Tripathi, Julien M. Buyck, Sandra Söderholm, Olivier Cunrath, Joseph Fanous, Beatrice Claudi, Adrian Egli, Christian Schleberger, Sebastian Hiller, Dirk Bumann
Abstract
growth in rich medium and consumption of diverse hydrophilic nutrients. However, preferred nutrients with two or more carboxylate groups such as succinate and citrate permeated poorly in the absence of porins. Porins provided efficient translocation pathways for these nutrients with broad and overlapping substrate selectivity while efficiently excluding all tested antibiotics except carbapenems, which partially entered through OprD. Porin-independent permeation of antibiotics through the outer-membrane lipid bilayer was hampered by carboxylate groups, consistent with our nutrient data. Together, these results challenge common assumptions about the role of porins by demonstrating porin-independent permeation of the outer-membrane lipid bilayer as a major pathway for nutrient and drug entry into the bacterial cell.