The Complexities of Porin Genetic Regulation

Cruz, Miguel A. De la; Calva, Edmundo

doi:10.1159/000274309

Cited by 52 publications

(47 citation statements)

References 239 publications

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“…Interestingly, during the medium shift, we observed the same regulation behaviour for porin and OmpX 2007). This finding suggests a more complex regulator cascade in addition to the TCS such as OmpREnvZ (De la Cruz & Calva, 2010;Fernández & Hancock, 2012;Masi & Pagès, 2013) in the studied strains. Moreover, we obtained different porin profiles, including porin absence or changes in porin level, with the various isolates treated under the various conditions.…”

Section: Discussionsupporting

confidence: 71%

Role of the culture medium in porin expression and piperacillin-tazobactam susceptibility in Escherichia coli

Pinet

Franceschi

Davin-Régli

et al. 2015

Journal of Medical Microbiology

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The continuing emergence of the multidrug resistance phenotype in Gram-negative bacteria makes the development of rapid susceptibility tests mandatory. To achieve this goal, proprietary specific media for bacterial growth can be used but may have some adverse effects. In this study, we dissected the role of media on porin, efflux pump and b-lactamase expression. Depending on the medium used, we observed a change in piperacillin-tazobactam susceptibility for some isolates, such as increases in MIC values. No significant alteration in efflux activity or in b-lactamase production was detected after changing the incubation medium. The ratio of piperacillinase:nitrocefinase showed no specific alteration, indicating that the various media did not affect significantly the relative enzymic affinity for the substrates. In contrast, osmotic variation was able to modulate both porin expression and OmpC : OmpF balance, thus modulating the antibiotic uptake. This study suggests that porin expression may be impacted by a susceptibility testing medium, which may modify the antibiotic diffusion into the bacteria, thus affecting MIC results.

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Section: Discussionsupporting

confidence: 71%

Role of the culture medium in porin expression and piperacillin-tazobactam susceptibility in Escherichia coli

Pinet

Franceschi

Davin-Régli

et al. 2015

Journal of Medical Microbiology

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“…JIE2753 had a substitution in the hydrophobic core of the signal peptide (Val10Glu) that might affect the correct secretion of the protein (61,62), but this was not explored further. Likewise, changes in regulatory factors that might affect porin expression (63) were not analyzed. The E. coli equivalent osmoporin gene ompC and promoter sequences in JIE121 (ETP MIC, 2 mg/liter) and JIE2558 (ETP MIC, 8 mg/liter) were intact, but the outer membrane protein profile of these isolates showed a pattern different from that of the wild-type strain ATCC 25922 (23) (see Fig.…”

Section: Discussionmentioning

confidence: 99%

Predictability of Phenotype in Relation to Common β-Lactam Resistance Mechanisms in Escherichia coli and Klebsiella pneumoniae

et al. 2016

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cThe minimal concentration of antibiotic required to inhibit the growth of different isolates of a given species with no acquired resistance mechanisms has a normal distribution. We have previously shown that the presence or absence of transmissible antibiotic resistance genes has excellent predictive power for phenotype. In this study, we analyzed the distribution of six ␤-lactam antibiotic susceptibility phenotypes associated with commonly acquired resistance genes in Enterobacteriaceae in Sydney, Australia. Escherichia coli (n ‫؍‬ 200) and Klebsiella pneumoniae (n ‫؍‬ 178) clinical isolates, with relevant transmissible resistance genes (bla TEM , n ‫؍‬ 33; plasmid AmpC, n ‫؍‬ 69; extended-spectrum ␤-lactamase [ESBL], n ‫؍‬ 116; and carbapenemase, n ‫؍‬ 100), were characterized. A group of 60 isolates with no phenotypic resistance to any antibiotics tested and carrying none of the important ␤-lactamase genes served as comparators. The MICs for all drug-bacterium combinations had a normal distribution, varying only in the presence of additional genes relevant to the phenotype or, for ertapenem resistance in K. pneumoniae, with a loss or change in the outer membrane porin protein OmpK36. We demonstrated mutations in ompK36 or absence of OmpK36 in all isolates in which reduced susceptibility to ertapenem (MIC, >1 mg/liter) was evident. Ertapenem nonsusceptibility in K. pneumoniae was most common in the context of an OmpK36 variant with an ESBL or AmpC gene. Surveillance strategies to define appropriate antimicrobial therapies should include genotype-phenotype relationships for all major transmissible resistance genes and the characterization of mutations in relevant porins in organisms, like K. pneumoniae. E scherichia coli and Klebsiella pneumoniae are among the most important pathogens in community and hospital settings, and their increasing resistance to extended-spectrum (third-and fourth-generation) cephalosporin and carbapenem antibiotics is a major health threat. In Gram-negative bacteria, such as these, a variety of mechanisms may confer ␤-lactam resistance (1), but the spread of transmissible genes encoding extended-spectrum ␤-lactamases (ESBLs) (2), plasmid-mediated AmpC ␤-lactamases (pAmpCs) (3), and carbapenemases (4) is particularly significant. Carbapenems have been the antibiotics of choice for treating ESBLs and other multidrug-resistant strains, but carbapenem resistance is increasingly common (5). This is mostly attributed to the production of specific carbapenemases (6), but the expression of AmpC or ESBL enzymes in isolates with altered outer membrane porins is also associated with decreased susceptibility to carbapenems (7-9). Mutations in major outer membrane porins may be required for clinically relevant carbapenem resistance in K. pneumoniae isolates expressing carbapenemases, such as KPC and OXA-48-like enzymes, which rarely elicit clinically important antibiotic resistance in E. coli (6).The clinical definitions of antibiotic susceptibility are developed by the collection and analysis of...

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“…In Escherichia coli and closely related organisms, this alteration is accomplished in part by changing the relative expression of two porins, OmpF and OmpC (17,44,46). Both OmpF and OmpC form structurally similar outer membrane pores comprising trimers of 16-stranded ␤-barrels (2, 13).…”

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confidence: 99%

Role of the mar-sox-rob Regulon in Regulating Outer Membrane Porin Expression

Chubiz

Rao

2011

J Bacteriol

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Multiple factors control the expression of the outer membrane porins OmpF and OmpC in Escherichia coli. In this work, we investigated the role of the mar-sox-rob regulon in regulating outer membrane porin expression in response to salicylate. We provide both genetic and physiological evidence that MarA and Rob can independently activate micF transcription in response to salicylate, leading to reduced OmpF expression. MarA was also found to repress OmpF expression through a MicF-independent pathway. In the case of OmpC, we found that its transcription was moderately increased in response to salicylate. However, this increase was independent of MarA and Rob. Finally, we found that the reduction in OmpF expression in a tolC mutant is due primarily to Rob. Collectively, this work further clarifies the coordinated role of MarA and Rob in regulating the expression of the outer membrane porins.

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The Complexities of Porin Genetic Regulation

Cited by 52 publications

References 239 publications

Role of the culture medium in porin expression and piperacillin-tazobactam susceptibility in Escherichia coli

Role of the culture medium in porin expression and piperacillin-tazobactam susceptibility in Escherichia coli

Predictability of Phenotype in Relation to Common β-Lactam Resistance Mechanisms in Escherichia coli and Klebsiella pneumoniae

Role of the mar-sox-rob Regulon in Regulating Outer Membrane Porin Expression

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