Diffusion of beta-lactam antibiotics through liposome membranes containing purified porins

Kobayashi, Yoriko; Takahashi, Ikuko; Nakae, Taiji

doi:10.1128/aac.22.5.775

Cited by 33 publications

(20 citation statements)

References 24 publications

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“…This possibility is supported by the observation that the mutants have a higher rate of [14C]maltose uptake than the parent strain does. In addition, the ompC mutants exhibited a significant increase in sensitivity to only certain antibiotics, namely, ampicillin, benzylpenicillin, and chloramphenicol, which are thought to penetrate the cell through porin proteins (14,27,29). Furthermore, these mutants are unaffected in their sensitivity to hydrophobic antibiotics, such as novobiocin, erythromycin, and rifampin, which are thought to enter the cell in ways other than through porins (27).…”

Section: Discussionmentioning

confidence: 99%

Isolation and characterization of OmpC porin mutants with altered pore properties

Misra

Benson

1988

J Bacteriol

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The LamB protein is normally required for the uptake of maltodextrins. Starting with a LamB-OmpFstrain, we have isolated mutants that will grow on maltodextrins. The mutation conferring the Dex+ phenotype in the majority of these mutants has been mapped to the ompC locus. These mutants, unlike LamB-OmpFstrains, grew on maltotriose and maltotetraose, but not on maltopentaose, and showed a significantly higher rate of [I4CJmaltose uptake than the parent strain did. In addition, these mutants showed increased sensitivity to certain j3-lactam antibiotics and sodium dodecyl sulfate, but did not exhibit an increase in sensitivity to other antibiotics and detergents. The nucleotide sequence of these mutants has been determined. In all cases, residue 74 (arginine) of the mature OmpC protein was affected. The results suggest that this region of the OmpC protein is involved in the pore domain and that the alterations lead to an increased pore size.

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Section: Discussionmentioning

confidence: 99%

Isolation and characterization of OmpC porin mutants with altered pore properties

Misra

Benson

1988

J Bacteriol

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“…Cells were grown in L-broth as described earlier [20] and the OmpF porins were purified by the procedure described previously [20].…”

Section: Bacterial Strain Undgrowth Conditionsmentioning

confidence: 99%

“…A typical reaction mixture contained 1 mM Tos-Arg-OMe and the vesicles (0.25 pmol phosphatidylcholine). The permeability parameter was calculated as described [20].…”

Section: Permeability Assaymentioning

confidence: 99%

The mechanism of ion selectivity of OmpF‐porin pores of Escherichia coli

Kobayashi

Nakae

1985

European Journal of Biochemistry

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The OmpF porin from the outer membrane of Escherichia coli acts as a lightly cation-selective pore, allowing the diffusion of small cations and cationic molecules, whose M , are a little larger than the threshold exclusion limit. To ascertain the mechanism of this cation selectivity, we have examined a possible influence of cationic solutes on the fluorescence emission and the circular dichroic spectrum of tryptophan residues of the porin trimer, searching for conformational change(s). The diffusion of cationic solutes was determined with the native and the amidated porins in the presence or the absence of the effector cations. The.fol1owing results were obtained. (a) Cations, e.g. spermidine, caused fluoresence quenching in the native trimer, with a half-maximum fluorescence quenching at 11 -18 pM. A change in the circular dichroic spectrum was also recorded at around 280 nm. (b) The dissociation constant of spermidine to the native trimer was calculated to be 16 pM as determined by the method of equilibrium dialysis. (c) The cation-caused fluorescence quenching was reversed when the carboxyl groups of the trimer were modified by the amidation reaction, though amidation of the trimer resulted in no significant change in the fluorescence intensity. (d) The diffusion rate of N-benzyloxycarbonyl-glycyl-L-proly1-Larginine p-nitroanilide through the native and the amidated porins was lowered in the presence and the absence, respectively, of cations. Both the extent of fluorescence quenching in the presence of cation and the rate of cation diffusion were inversely proportional to the number of amidated carboxyl residues. The relative fluorescence quenching of the porin trimer (the amidated versus the native) in the presence of cations was linearly related to the relative solute diffusion via the porin (the amidated versus the native). These results suggested that cations caused a conformational change in the trimer, resulting in an easier diffusion of the solutes. The results suggested further that a limited number of carboxyl groups in the pore interior are involved in the cation selectivity of OmpF-porin pores.The outer membrane of gram-negative bacteria such as Escherichia ccdi and Salmonella species acts as a penetration barrier against hydrophobic compounds (see [l] for a review) and uncharged sugars of M , over 500 [2, 31. The outer membrane, on the other hand, allows the diffusion of small hydrophilic molecules through the porin pores [3, 41 with relatively low solute selectivity. E. coli K12 produces three species of closely related porins such as OmpF, OmpC and PhoE, named according to their genes (see [5] for a review). These proteins were, however, shown to be distinct polypeptides by chemical analyses [6, 71 and to be coded for by different structural genes [S -101.Close examination of the permeability properties of these porins, by ion conductivity measurements using a black lipid bilayer, revealed that the OmpF porin of E. coli and of Salmonella thyphimurium allowed 3 -5-fold more efficient diffusion o...

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“…In some species, such as Enterobacter cloacae, Citrobacterfreundii, and Pseudomonas aeruginosa, the enzymes may be induced by ,-lactams (16). The molecular basis of P-lactamase induction is not fully understood, but in E. cloacae and C. freundii, expression of the ampC P-lactamase gene is regulated by the ampR gene product (7), which is in turn controlled by the products of at least four other genes, ampD, ampE, pbpA, and ampG (5,6,15).…”

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confidence: 99%

Induction of the Citrobacter freundii group I beta-lactamase in Escherichia coli is not dependent on entry of beta-lactam into the cytoplasm

Everett

Chopra

Bennett

1990

Antimicrob Agents Chemother

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Diffusion of beta-lactam antibiotics through liposome membranes containing purified porins

Cited by 33 publications

References 24 publications

Isolation and characterization of OmpC porin mutants with altered pore properties

Isolation and characterization of OmpC porin mutants with altered pore properties

The mechanism of ion selectivity of OmpF‐porin pores of Escherichia coli

Induction of the Citrobacter freundii group I beta-lactamase in Escherichia coli is not dependent on entry of beta-lactam into the cytoplasm

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