Uptake of aminoglycosides through outer membrane porins in Escherichia coli

Aminoglycosides are important clinical antibiotics but their molecular uptake mechanism is still not completely understood. Here we quantify and compare the passive transport of three aminoglycosides (kanamycin, gentamicin, and amikacin) across general or sugar specific porins of Escherichia coli (OmpF, OmpC, LamB and ChiP). Our analysis revealed that permeation of aminoglycosides (Kanamycin/Gentamycin/Amikacin) is about the same through ChiP (≈5/3/2 molecules/s), OmpF (≈10/15/<1 molecules/s) and OmpC (≈11/8/<1 molecules/s). In contrast, LamB of smaller pore diameter has no significant permeation (≤1/1/1 molecules/s, all values recalculated for a gradient of 10 µM). Biological assays confirmed the relevance of these translocations for antibiotic potency.