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Structure-kinetic relationship of carbapenem antibacterials permeating through E. coli OmpC porin

Tran, Que Tien, Pearlstein, Robert, Williams, Sarah, Reilly, John, Krucker, Thomas and Erdemli, Gul (2014) Structure-kinetic relationship of carbapenem antibacterials permeating through E. coli OmpC porin. Proteins: Structure, Function and Bioinformatics, 82 (11). pp. 2998-3012. ISSN 08873585


The outer membrane (OM) of Gram-negative bacteria contains lipopolysaccharide outer leaflet, which slows the direct cellular penetration of polar low molecular weight substances, including antibiotics. Instead, such molecules are believed to translocate into the periplasm through water-filled channels that span the OM. In our previous work, we proposed a novel mechanism of antibiotic translocation through E. coli OmpC, in which the solvation structure of the channel governs antibacterial association and dissociation barriers, and demonstrated a qualitative correlation with published electrophysiological kinetics data for six antibiotics. Here, we investigate the structure-translocation kinetics relationships of a set of carbapenem antibacterials through OmpC. Susceptibility to carbapenems increased when recombinant OmpC was expressed as the major porin in the porin-depleted E. coli omp8 strain, suggesting that OmpC serves as an important uptake route for these antibacterials. In agreement with susceptibility data, electrophysiology studies with purified OmpC reconstituted in phospholipid bilayers suggest that the structure-kinetic relationships of carbapenem translocation are governed largely by H-bond acceptor/donor composition. Ertapenem, which contains an additional acidic group compared to other analogs, exhibited the fastest entry into OmpC (kon  2x104 M-1s-1). Zwitterionic compounds with highly polar groups attached to the penem-2 ring, including panipenem, imipenem and doripenem showed faster kon (>104 M-1s-1), while meropenem and biapenem with fewer exposed polar groups exhibited slower kon (~5x103 M-1s-1). Tebipenem pivoxil and razupenem exhibited the slowest kon of the compounds in the data set (~1.5x103 M-1s-1). Our study provides useful insights that may aid the design of antibacterials with improved rates of intracellular entry via porins.

Item Type: Article
Keywords: Gram-negative bacteria, porin OmpC, carbapenem antibacterials, translocation kinetics, structure-activity relationship
Date Deposited: 13 Oct 2015 13:13
Last Modified: 04 Jul 2016 23:46


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