Drug Resistance of Enteric Bacteria

Sawai, Tetsuo; Mitsuhashi, Susumu; Yamagishi, Saburo

doi:10.1111/j.1348-0421.1968.tb00415.x

Cited by 96 publications

(8 citation statements)

References 14 publications

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“…marcescens. The purified cephalosporinase from S. marcescens GN7647 showed the same general properties as for typical cephalosporinases described by Sawai et al (1968) and for class I P-lactamases described by Richmond & Sykes (1973). As indicated by Vmax values, this enzyme has a high activity on cephalosporin derivatives and a low activity for semi-synthetic penicillins, some novel cephalosporins and cephamycins.…”

Section: Farrarsupporting

confidence: 58%

Purification and Properties of -Lactamases from Serratia marcescens

et al. 1981

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Both a penicillinase and a cephalosporinase were purified from a strain of Serratia marcescens (GN7647) resistant to P-lactam antibiotics. The penicillinase was identical to the type I penicillinase, mediated by Rms2 12 and R-TEM. The purified cephalosporinase, a typical chromosomally mediated enterobacterial P-lactamase, gave a single protein band on polyacrylamide gel electrophoresis and immunoelectrophoresis; the PI was 9.56 and its molecular weight was approximately 37 000. It contained tryptophan but not cysteine. The specific activity was 374 units (mg protein)-' for the hydrolysis of cephaloridine, and the optimal pH was 8.5. Rabbit antisera raised against the purified cephalosporinase showed no cross-reaction in a neutralization test with cephalosporinases produced by other species of Enterobacteriaceae.

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Section: Farrarsupporting

confidence: 58%

Purification and Properties of -Lactamases from Serratia marcescens

et al. 1981

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“…In the preceding studies [2, 5-71, we selected the cephalosporinase of Citrobucter,freundii GN346 as a representative cephalosporinase of Gram-negative bacteria and its characteristics were extensively investigated. C. freundii GN346 was isolated from a clinical source in Japan in 1965, and produces a chromosomal p-lactamase exhibiting the substrate profile of a typical cephalosporinase [8]. The cephalosporinase is synthesized through a unique regulatory mechanism of thermolabile repression [9].…”

mentioning

confidence: 99%

Role of lysine‐67 in the active site of class C β‐lactamase from Citrobacter freundii GN346

Tsukamoto

Tachibana

Yamazaki

et al. 1990

European Journal of Biochemistry

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Citrohacter freundii GN346 produces a class C p-lactamase exhibiting the substrate profile of a typical cephalosporinase. The structural and promoter regions of the cephalosporinase gene, comprising 1408 nucleotides, were completely sequenced. The amino acid sequence of the mature enzyme, comprising 361 amino acids, and its molecular mass, 39 878 Da, were determined. The active site was confirmed to be Ser-64. The amino acid sequence of the enzyme differs from that of the cephalosporinase of C. jreundii OS60 by nine residues. The nucleotide sequence of the promoter region suggests a possible attenuator structure. Lys-67, one of the most conserved residues found in class A and C p-lactamases and penicillin-binding proteins, was converted into arginine, threonine or glutamic acid through site-directed mutagenesis. The Glu-67 enzyme had lost the catalytic activity and the Thr-67 enzyme only showed a trace of activity. The Arg-67 enzyme, which retained a significant amount of the activity, was purified. The K, values of the Arg-67 enzyme for cephalothin, cephaloridine and benzylpenicillin are 13-19 times those of the wild-type enzyme; the k,,, values for the three substrates are 37%, 3%, and 36% those of the wild-type enzyme, respectivelyThe cephalosporinases found in a large number of Gramnegative bacteria are species-specific p-lactamases [I, 21. These p-lactamases belong to class C, according to Ambler's classification based on the amino acid sequence around the active site [3]. In the clinical field, cephalosporinases are of importance because clinical isolates producing cephalosporinases show high levels of resistance to both cephalosporins and penicillins [4]. In the preceding studies [2, 5-71, we selected the cephalosporinase of Citrobucter,freundii GN346 as a representative cephalosporinase of Gram-negative bacteria and its characteristics were extensively investigated. C. freundii GN346 was isolated from a clinical source in Japan in 1965, and produces a chromosomal p-lactamase exhibiting the substrate profile of a typical cephalosporinase [8]. The cephalosporinase is synthesized through a unique regulatory mechanism of thermolabile repression [9]. It is synthesized semiconstitutively when the bacterium is cultured at above 25"C, whereas the enzyme synthesis requires a chemical inducer such as benzylpenicillin at 20 "C. The cephalosporinase gene of GN346 was cloned into a vector plasmid and its expression in Escherichia coli was confirmed [lo]. Recently, the structural gene for the enzyme was sequenced and a preliminary report of the amino acid sequence of the mature enzyme has been presented at a symposium [7].

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“…The following three /J-lacta mase producers were used: Escherichia coli ML 1410 RGN823, E. coli MLI410 RGN238 and E. coli NIH JC-2 (12,14,15). The other strain used w asastandard strain of Micrococcus luteus ATCC934I.…”

Section: Methodsmentioning

confidence: 99%

A Novel Method for Determination of β-Lactamase Using the Agar Dilution Method

Tsuji¹

1983

Chemotherapy

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A novel test procedure is described for the rapid assay of β-Lactamase using the agar dilution method. The susceptibility to β-Lactamase was measured by adding an appropriate amount of enzyme to the diluting culture broth of a test organism in the agar dilution method. By this method, β-Lactamase susceptibility can be expressed in the same way as the MIC assay for antibiotics (µg/ml). The results obtained with Escherichia coli β-Lactamase were closely related to the MIC patterns of the strains producing β-Lactamases.

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Drug Resistance of Enteric Bacteria

Cited by 96 publications

References 14 publications

Purification and Properties of -Lactamases from Serratia marcescens

Purification and Properties of -Lactamases from Serratia marcescens

Role of lysine‐67 in the active site of class C β‐lactamase from Citrobacter freundii GN346

A Novel Method for Determination of β-Lactamase Using the Agar Dilution Method

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