Uptake of aminoglycosides through outer membrane porins in Escherichia coli

Abstract

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 uM). Biological assays confirmed the relevance of these translocations for antibiotic potency.

Fosfomycin Uptake in Escherichia coli Is Mediated by the Outer-Membrane Porins OmpF, OmpC, and LamB

“…Consistently, OmpF and OmpC-mediated resistances in E. coli were previously shown for different classes of β-lactams such as carbapenems, penicillins, cephalosporins, ,,− as well as fluoroquinolones, colicin and kanamycin. , In addition, OmpF-related resistance alone was reported for the antibiotics tetracycline, aztreonam, cinoxacin, and clindamycin, and OmpC was related to an increased resistance to trimethoprim, tetracycline and cefepime …”

“…Indeed, ChiP (2.5 TPM in LB medium, Figure S6) was shown to still be sufficient to internalize the aminoglycosides kanamycin, gentamycin, and amikacin. 52 Another intriguing result was that the transcripts for UhpT and GlpT inner-membrane transporters are much less abundant in comparison to the transcripts for OmpF, OmpC, and LamB (Figure 5), suggesting that the IM, rather than the OM might be the rate-limiting barrier for FOS uptake in LB. In agreement, we showed the role of the OmpF, OmpC, and LamB porins for the uptake of the drug only upon UhpT-inducing conditions (Figures 1−3).…”

“…As FOS is a very small molecule, we expected that other OM channels could be relevant for its transport, even when transcribed in few copies. Indeed, ChiP (2.5 TPM in LB medium, Figure S6) was shown to still be sufficient to internalize the aminoglycosides kanamycin, gentamycin, and amikacin . Another intriguing result was that the transcripts for UhpT and GlpT inner-membrane transporters are much less abundant in comparison to the transcripts for OmpF, OmpC, and LamB (Figure ), suggesting that the IM, rather than the OM might be the rate-limiting barrier for FOS uptake in LB.…”

“…Consistently, OmpF and OmpC-mediated resistances in E. coli were previously shown for different classes of β-lactams such as carbapenems, penicillins, cephalosporins, 22,44,46−49 as well as fluoroquinolones, 50 colicin 51 and kanamycin. 45,52 In addition, OmpF-related resistance alone was reported for the antibiotics tetracycline, aztreonam, cinoxacin, and clindamycin, 44 and OmpC was related to an increased resistance to trimethoprim, 53 tetracycline 54 and cefepime. 55 Besides confirming the prevalent role of OmpF and for the first time demonstrating a contribution of OmpC in FOS translocation, we further revealed the role of LamB in the uptake of FOS by continuous turbidimetric monitoring of E. coli growth in liquid LB medium and by gradient strip test on LB agar plates supplemented with 100 μM maltotriose (Figures 3 and S4).…”