Outer membrane permeability in Pseudomonas cepacia: diminished porin content in a beta-lactam-resistant mutant and in resistant cystic fibrosis isolates

Aronoff, Stephen C.

doi:10.1128/aac.32.11.1636

Cited by 70 publications

(43 citation statements)

References 26 publications

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“…Mechanisms of resistance to P-lactams include enzymic degradation of the antibiotic by p-lactamases or exclusion-of the antibiotic from its site of action by impermeability. In the latter case, resistance to Plactams in P. cepacia has been shown to be associated with mutations of outer membrane protein (porins) genes (18). We were unable to detect any change in expression of outer membrane proteins, in particular in the 36 kD porin in our isolates under the different growth conditions.…”

Section: Discussioncontrasting

confidence: 45%

Effect of pH and CO2 on In Vitro Susceptibility of Pseudomonas cepacia to β-Lactams

et al. 1994

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ABSTRACT. Inhibition of Pseudomonas cepacia (but not Pseudomonas aeruginosa) by &lactams was decreased in 5% C 0 2 in air compared with air alone. The effect of C 0 2 and p H (range, 6.0 to 8.0) on 8-lactam susceptibility, 8-lactamase expression, and outer membrane proteins was studied in isolates recovered from the sputum of children with cystic fibrosis. Incubation in 5% COz decreased the activity of piperacillin, piperacillin/tazobactam, and ceftazidime, although isolates were still clinically sensitive (minimum inhibitory concentrations < 16 mg/L). Cefpirome activity was markedly decreased from a minimum inhibitory concentration of 2.0 to greater than 64 mg/L. On highly buffered 3-(N-morpho1ino)-propane sulfonic acid media, b-lactam susceptibility was eliminated at pH greater 7.5. A 2-to 13-fold increase in @-lactamase activity was demonstrated after growth in 5% C 0 2 compared with basal aerobic levels for 13 of 15 clinical isolates. 8-Lactamase activity did not vary significantly with pH. Addition of imipenem to media (2.0 mg/L) resulted in hyperproduction of 8-lactamase (180-fold). Isoelectric points varied with cultural conditions, and all 8-lactamases detected were inhibited by clavulanate and tazobactam. Significant hydrolysis of piperacillin and ceftazidime could not be demonstrated. A 36-kD porin was present a t all pII tested. Thus, our strains of Pseudomonas cepacia were markedly affected by cultural conditions not normally used in standardized susceptibility tests. However, such conditions may be encountered in the pathologically altered infected lung in cystic fibrosis. (Pediatr Res 35: [299][300][301][302] 1994) Abbreviations O M P , outer membrane protein MIC, minimum inhibitory concentration MOPS, 3-(N-morpholino)-propane sulfonic acid HBMM, highly buffered M O P S media IS0, concentration of inhibitor required to inhibit enzymatic activity by 50% under defined assay conditionsPselidomonas cepacia has emerged as an important opportunist pathogen in pulmonary infections in children with cystic fibrosis (1-3) and its appearance is associated with increased morbidity and mortality (2). Many strains of P. ccpacia are

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Section: Discussioncontrasting

confidence: 45%

Effect of pH and CO2 on In Vitro Susceptibility of Pseudomonas cepacia to β-Lactams

et al. 1994

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“…(1987) and confirmed by Aronoff (1988) and Burns & Clark (1992). No further dissociation of the oligomer into the two proteins was achieved by prolonged heating (data not shown).…”

Section: Purification Of Opcpo Opcpl and Opcp2mentioning

confidence: 87%

“…However, the 81 kDa protein which we have designated OpcPO in the B. cepacia outer membrane dissociates into two proteins with different mobilities on SDS-PAGE gels (Parr e t al., 1987). Although this unique heterogeneity of OpcPO has been confirmed by several investigators (Aronoff, 1988;Burns & Clark, 1992), there is little information on the relationship between these proteins. Prior to investigation of the individual functions of the proteins derived from OpcPO, it is important to resolve To resolve the above question, we independently purified OpcPl and OpcP2 from a preparation of OpcPO.…”

Section: Discussionmentioning

confidence: 99%

“…Investigation of the function and structure of the structurally unique 81 kDa protein as compared with the ordinary porin oligomer in Gram-negative bacteria (Nikaido & Vaara, 1985;Nakae, 1986;Benz, 1988;Nikaido & Red, 1990;Rosenbusch, 1990) might be useful not only for a general understanding of the drug resistance of B. cepacia, but also for understanding how porins assemble. Despite little information regarding the relationship between the 36 kDa and the 27 kDa proteins, they seem to have been recently accepted as independent components (Aronoff, 1988) or subunits (Burns & Clark, 1992) from which the 81 kDa protein is constructed.…”

Section: Introductionmentioning

confidence: 99%

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Burkholderia (formerly Pseudomonas) cepacia porin is an oligomer composed of two component proteins

Gotoh¹,

Nagino²,

Wada³

et al. 1994

Microbiology

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The 81 kDa protein (designated OpcPO) which forms a diffusion pore in the outer membrane of Burkholderia (formerly Pseudomonas) cepacia has a unique characteristic in that when the purified protein is heated it yields a major 36 kDa protein (designated OpcP1) and a minor 27 kDa protein (designated OpcP2). Moreover, incubation of OpcPO in citrate buffer at pH 3 9produced an unusual dissociation into 72 kDa and 27 kDa proteins. For the characterization of OpcPO and its derivatives, OpcPl and OpcP2 from purified OpcPO were isolated by preparative SDS-PAGE. Reconstitution of OpcPO using purified preparations of OpcPl and OpcP2 indicated that these derivatives were not proteolytic fragments of OpcPO. Moreover, immunoblot assays with murine polyclonal antisera specific for OpcPl and OpcP2 yielded the following results: (i) OpcPl and OpcP2 are immunologically distinguishable proteins; (ii) the unusual dissociation of OpcPO in citrate buffer at pH 3-0 resulted in the release of OpcP2 from opcPo# and the resulting 72 kDa protein was probably an oligomer of OpcP1; (iii) purified OpcPl itself produced two additional 53 kDa and 72 kDa proteins spontaneously following elution from the bottom of the SDS-PAGE gel. From these findings, it was concluded that OpcPO is formed by the non-covalent association of OpcP2 with an oligomer of OpcPl that has the ability to self-assemble.

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“…Finally, poor outer membrane permeability, which prevents exogenous elements from integrating into the intracellular environment, has been found in B. cenocepacia . Thus, this characteristic guarantees that the three chromosomes are well protected in a protective environment (Aronoff 1988). Above all, it is reasonable to recognize that the genes among the three chromosomes are stable for a long evolutionary period of time.…”

Section: Discussionmentioning

confidence: 96%

Analysis of genomic characters reveals that four distinct gene clusters are correlated with different functions in Burkholderia cenocepacia AU 1054

Yuan

Yang

Ren

et al. 2013

Appl Microbiol Biotechnol

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Possessing three circular chromosomes is a distinct genomic characteristic of Burkholderia cenocepacia AU 1054, a clinically important pathogen in cystic fibrosis. In this study, base composition, codon usage and functional role category were analyzed in the B. cenocepacia AU 1054 genome. Although no bias in the base and codon usage was detected between any two chromosomes, function differences did exist in the genes of each chromosome. Similar base composition and differential functional role categories indicated that genes on these three chromosomes were relatively stable and that a proper division of labor was established. Based on variations in the base or codon usage, four small gene clusters were observed in all of the genes. Multivariate analysis revealed that protein hydrophobicity played a predominant role in shaping base usage bias, while horizontal gene transfer and the gene expression level were the two most important factors that affected the codon usage bias. Interestingly, we also found that these gene clusters were correlated with different biological functions: (i) 45 pyrimidine-leadingcodon preferred genes were predominantly involved in regulatory function; (ii) most drug resistance-related genes involved in 826 genes that coding for hydrophobic proteins; (iii) most of the 111 horizontal transfer genes were responsible for genomic plasticity; and (iv) 73 highly expressed genes (predicted by their codon adaptation index values) showed environmental adaptation to cystic fibrosis. Our results showed that genes with base or codon usage bias were affected by mutational pressure and natural selection, and their functions could contribute to drug assistance and transmissible activity in B. cenocepacia.

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Outer membrane permeability in Pseudomonas cepacia: diminished porin content in a beta-lactam-resistant mutant and in resistant cystic fibrosis isolates

Cited by 70 publications

References 26 publications

Effect of pH and CO2 on In Vitro Susceptibility of Pseudomonas cepacia to β-Lactams

Effect of pH and CO2 on In Vitro Susceptibility of Pseudomonas cepacia to β-Lactams

Burkholderia (formerly Pseudomonas) cepacia porin is an oligomer composed of two component proteins

Analysis of genomic characters reveals that four distinct gene clusters are correlated with different functions in Burkholderia cenocepacia AU 1054

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