Salmonella typhimurium and Escherichia coli mutants with increased outer membrane permeability to hydrophobic compounds

Sukupolvi, Soila; Vaara, Martti

doi:10.1016/0304-4157(89)90011-7

Cited by 52 publications

(29 citation statements)

References 104 publications

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“…In contrast, no sensitization or very slight sensitization to antibiotics such as cefuroxime and benzylpenicillin, which use the porin channels, was observed (data not shown; see also reference 39). Furthermore, like other enteric bacteria which have a defective or damaged OM (28,37,40), the omsA strain showed no increased susceptibility to aminoglycoside antibiotics (data not shown; see also reference 39).…”

Section: Methodsmentioning

confidence: 71%

“…The omsA mutant strain was also susceptible to bacitracin and vancomycin (Table 2). Common to all of these antibiotics is the fact that they do not penetrate the enterobacterial OM through the water-filled, narrow porin chan- nels, since they are either hydrophobic molecules (rifampin, fusidic acid, erythromycin, mupirocin, and clindamycin) or large, hydrophilic molecules (bacitracin and vancomycin) (28,30,37,40). In contrast, no sensitization or very slight sensitization to antibiotics such as cefuroxime and benzylpenicillin, which use the porin channels, was observed (data not shown; see also reference 39).…”

Section: Methodsmentioning

confidence: 99%

“…Agents that damage the OM sensitize the bacteria drastically to hydrophobic inhibitors (40). Also, mutants which have severe defects in the nonessential inner carbohydrate core region of LPS (chemotypes Re, Rd2, Rd,, and RcP-) are supersusceptible (14,28,30,37). Therefore, supersusceptibility to hydrophobic drugs may suggest a defect in the OM.…”

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confidence: 99%

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Mutants carrying conditionally lethal mutations in outer membrane genes omsA and firA (ssc) are phenotypically similar, and omsA is allelic to firA

Vuorio

Vaara

1992

J Bacteriol

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We have previously identified the gene (the ssc gene) defective in the thermosensitive and antibiotic-supersusceptible outer membrane permeability mutant SS-C of Salmonella typhimurium and shown that this gene is analogous to the Escherichia coli gene firA (L. Hirvas, P. Koski, and M. Vaara, EMBO J. 10:1017-1023, 1991). Others have tentatively implicated firA in a different function, mRNA synthesis. Here we report that the defect in the thermosensitive outer membrane omsA mutant of E. coli (T. Tsuruoka, M. Ito, S. Tomioka, A. Hirata, and M. Matsuhashi, J. Bacteriol. 170:5229-5235, 1988) is due to a mutation in firA; this mutation changed codon 271 from serine to asparagine. The omsA-induced phenotype was completely reverted by plasmids containing wild-type firA or ssc. Plasmids carrying the omsA allele, or an identical mutant allele prepared by localized mutagenesis, under the control of lac elicited partial complementation. Transcomplementation studies with plasmids carrying various mutant alleles of the S. typhimurium gene indicated that the ability of these plasmids to complement the omsA mutation was similar to their ability to complement the ssc mutation. The antibiotic-supersusceptible phenotype of the omsA mutant closely resembled that of the ssc mutant, i.e., the omsA mutant was supersusceptible to hydrophobic antibiotics and large-peptide antibiotics against which the intact outer membrane is an effective permeability barrier. As previously demonstrated with the omsA mutant, the outer membrane of the ssc mutant became selectively ruptured after incubation for 1 h at the growth-nonpermitting temperature; 82% of the periplasmic beta-lactamase and less than 3% of the cytoplasmic marker enzyme were released into the medium. All of these findings are consistent with our concept that firA is an essential gene involved in generation of the outer membrane.

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Section: Methodsmentioning

confidence: 71%

Section: Methodsmentioning

confidence: 99%

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Mutants carrying conditionally lethal mutations in outer membrane genes omsA and firA (ssc) are phenotypically similar, and omsA is allelic to firA

Vuorio

Vaara

1992

J Bacteriol

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“…4). LPS consists of a hydrophobic lipid and hydrophilic polysaccharides, and is a component of the outer membrane of gram-negative bacteria (Sukupolvi and Vaara, 1989). The hydrophilic characteristics of the resistant strain may be due to the extension of the polysaccharide chain or an increase in the amount of LPS.…”

Section: Fig 2 Organic Solvent Resistance Of E Coli If012713mentioning

confidence: 99%

“…Among them, possible ways to resist biocides involve impermeability and efflux (Russell, 2001). It is known that impermeability is due to the cell surface structure, particularly, the lipopolysaccharides of Gram-negative bacteria (Sukupolvi and Vaara, 1989). Drug efflux systems which consist of membrane proteins are called efflux pumps.…”

Section: Introductionmentioning

confidence: 99%

Characterization and Protein Analysis of Escherichia coli Resistant to a Quaternary Ammonium Compound

et al. 2005

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A resistant strain of Escherichia coil IF012713, resistant against the quaternary ammonium compound (QAC), N-dodecylpyridinium iodide (P-12), was developed by using a standard broth dilution method and physiologically characterized by comparison to a sensitive strain. The cell surface hydrophobicity cultivated in the resistance-acquiring process gradually decreased and the lipopolysaccharides in the outer membrane increased. This result indicated that the cell surface of the resistant strain was more hydrophobic than that of the sensitive strain. One of the resistant strains isolated from the process also had resistance to other antibiotics and organic solvents. Rapid ethidium efflux was observed in the resistant strain compared to the sensitive strain. To elucidate the mechanism of resistance on a molecular level, protein analysis was performed with 2D-PAGE for the entire cellular fraction, and SDS-PAGE for the outer or inner membrane fractions. It was seen that 18 spots and bands of proteins specifically increased in the resistant strain. From the physiological characterization and the protein analysis, it was suggested that the QAC-resistant strain acquired its resistance by responding to antimicrobial stresses, stabilizing the outer membrane to control the adsorption/ binding reaction between the cell and agent, and activating the efflux pump against the antimicrobial agents.

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Identification and sequence analysis of the gene mutated in the conditionally lethal outer membrane permeability mutant SS-C of Salmonella typhimurium.

1991

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The biosynthesis and structure‐function relationships of the enterobacterial outer membrane are subjects of current intensive research. We have previously described the antibiotic supersensitive SS‐C mutant (SH7622) of Salmonella typhimurium and shown that its outer membrane permeability barrier against hydrophobic antibiotics is severely defective. In this study, we show that this mutant is heat‐sensitive, conditionally lethal, and carries a missense base‐pair substitution in a novel gene which we have recently reported and now named the ssc gene. ssc encodes an earlier uncharacterized 36 kd protein (the Ssc protein) and the mutant expresses Ssc which has valine 291 changed to methionine in a methionine‐rich region of Ssc. A plasmid containing the wild‐type ssc allele completely reverts the antibiotic‐ and heat‐sensitive phenotype of the SS‐C mutant. Corresponding plasmids carrying the mutant allele, or an identical mutant allele prepared by localized mutagenesis, are inactive. The ssc gene is probably analogous to the firA locus of Escherichia coli which has earlier been implicated in a totally different function, mRNA synthesis. Furthermore, ssc apparently lies very close to the lpx genes involved in the thus far known steps of lipid A biosynthesis (the distance, approximately 560 bp). To conclude, our findings define a new essential gene involved in the generation of the outer membrane.

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Salmonella typhimurium and Escherichia coli mutants with increased outer membrane permeability to hydrophobic compounds

Cited by 52 publications

References 104 publications

Mutants carrying conditionally lethal mutations in outer membrane genes omsA and firA (ssc) are phenotypically similar, and omsA is allelic to firA

Mutants carrying conditionally lethal mutations in outer membrane genes omsA and firA (ssc) are phenotypically similar, and omsA is allelic to firA

Characterization and Protein Analysis of Escherichia coli Resistant to a Quaternary Ammonium Compound

Identification and sequence analysis of the gene mutated in the conditionally lethal outer membrane permeability mutant SS-C of Salmonella typhimurium.

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