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At least 19 recordsLinked to original sources
PubMed1970

Mechanism of D-cycloserine action: transport systems for D-alanine, D-cycloserine, L-alanine, and glycine.

The accumulation of d-alanine, l-alanine, glycine, and d-cycloserine in Escherichia coli was found to be mediated by at least two transport systems. The systems for d-alanine and glycine are related, and are separate from that involved in the accumulation of l-alanine. d-Cycloserine appears to be primarily transported by the d-alanine-glycine system. The accumulation of d-alanine, glycine, and d-cycloserine was characterized by two line segments in the Lineweaver-Burk analysis, whereas the accumulation of l-alanine was characterized by a single line segment. d-Cycloserine was an effective inhibitor of glycine and d-alanine accumulation, and l-cycloserine was an effective inhibitor of l-alanine transport. The systems were further differentiated by effects of azide, enhancement under various growth conditions, and additional inhibitor studies. Since the primary access of d-cycloserine in E. coli is via the d-alanine-glycine system, glycine might be expected to be a better antagonist of d-cycloserine inhibition than l-alanine. Glycine and d-alanine at 10(-5)m antagonized the effect of d-cycloserine in E. coli, whereas this concentration of l-alanine had no effect.

Alanine↗
PubMed1991

Evaluation of cycloserine-cefoxitin-fructose agar and cycloserine-cefoxitin-fructose broth for recovery of Clostridium difficile from environmental sites.

Cycloserine-cefoxitin-fructose agar (CCFA) and cycloserine-cefoxitin-fructose broth (CCFB) containing either 500 or 250 micrograms of cycloserine per ml were compared for efficacy in the isolation of Clostridium difficile from hospital ward environmental sites. A RODAC imprint technique was used to inoculate prereduced CCFA. Moistened swabs were used to inoculate prereduced CCFB from environmental sites immediately adjacent to the RODAC sample sites. CCFA (6% positive) was significantly more sensitive than CCFB (3% positive; P less than 0.005), regardless of the cycloserine concentration. When the CCFA cycloserine concentration was decreased from 500 to 250 micrograms/ml, the overall rate of positive cultures rose from 4 to 17%. Medium containing 500 micrograms of cycloserine per ml may be too inhibitory to isolate many moderately sensitive strains of C. difficile from environmental sites. Regardless of the cycloserine concentration, the CCFA RODAC imprint technique is superior to the CCFB method.

Agar↗
PubMed1971

Mechanism of D-cycloserine action: transport mutants for D-alanine, D-cycloserine, and glycine.

The accumulation of d-alanine and the accumulation of glycine in Escherichia coli are related and appear to be separate from the transport of l-alanine. The analysis of four d-cycloserine-resistant mutants provides additional support for this conclusion. The first-step mutant from E. coli K-12 that is resistant to d-cycloserine was characterized by the loss of the high-affinity line segment of the d-alanine-glycine transport system in the Lineweaver-Burk plot. This mutation, which is linked to the met(1) locus, also resulted in the loss of the ability to transport d-cycloserine. The second-step mutation that is located 0.5 min from the first-step mutation resulted in the loss of the low-affinity line segment for the d-alanine-glycine transport system. The transport of l-alanine was decreased only 20 to 30% in each of these mutants. A multistep mutant from E. coli W that is 80-fold resistant to d-cycloserine lost >90% of the transport activity for d-alanine and glycine, whereas 75% of the transport activity for l-alanine was retained. E. coli W could utilize either d- or l-alanine as a carbon source, whereas the multistep mutant could only utilize l-alanine. Thus, a functioning transport system for d-alanine and glycine is required for both d-cycloserine action and growth on d-alanine.

Alanine↗
PubMed1997

Comparison of a new, bismuth-iron-sulfite-cycloserine agar for isolation of Clostridium perfringens with the tryptose-sulfite-cycloserine and blood agars.

A new differential and selective, bismuth-iron-sulfite-cycloserine (BISC) medium, for isolation and enumeration of Clostridium perfringens from food and feces, was developed. The medium was compared with the widely-used tryptose-sulfite-cycloserine (TSC) medium and blood agar (BA) in recovering actively growing cells, cold- (refrigerated and frozen) stressed, and heat-stressed C. perfringens cells, and heat-activated spores from human feces. Both selective media were satisfactory in recovering actively growing cells and heat-activated spores of C. perfringens. Both were inferior to non-inhibitory blood agar in recovering heat or cold-stressed cells. The advantages of the new BISC medium over the TSC medium were: elimination of the need to prepare pour- or overlay-agar plates, which simplified inoculation of specimens on the medium and simplified the subcultures of colonies for confirmatory identification. All colonies of C. perfringens developed on BISC were black or dark gray. This was contrary to TSC medium, which gave, on average, 39.6% of white colonies when inoculated with the pure cultures of C. perfringens.

Bacteriological Techniques↗
PubMed2004

Self-protection mechanism in D-cycloserine-producing Streptomyces lavendulae. Gene cloning, characterization, and kinetics of its alanine racemase and D-alanyl-D-alanine ligase, which are target enzymes of D-cycloserine.

An antibiotic, D-cycloserine (DCS), inhibits the catalytic activities of alanine racemase (ALR) and d-alanyl-d-alanine ligase (DDL), which are necessary for the biosynthesis of the bacterial cell wall. In this study, we cloned both genes encoding ALR and DDL, designated alrS and ddlS, respectively, from DCS-producing Streptomyces lavendulae ATCC25233. Each gene product was purified to homogeneity and characterized. Escherichia coli, transformed with a pET vector carrying alrS or ddlS, displays higher resistance to DCS than the same host carrying the E. coli ALR- or DDL-encoded gene inserted into the pET vector. Although the S. lavendulae DDL was competitively inhibited by DCS, the K(i) value (920 microM) was obviously higher (40 approximately 100-fold) than those for E. coli DdlA (9 microM) or DdlB (27 microM). The high K(i) value of the S. lavendulae DDL suggests that the enzyme may be a self-resistance determinant in the DCS-producing microorganism. Kinetic studies for the S. lavendulae ALR suggest that the time-dependent inactivation rate of the enzyme by DCS is absolutely slower than that of the E. coli ALR. We conclude that ALR from DCS-producing S. lavendulae is also one of the self-resistance determinants.

Alanine Racemase↗
PubMed2003

Molecular cloning of a D-cycloserine resistance gene from D-cycloserine-producing Streptomyces garyphalus.

A 3.5-kb DNA fragment that confers resistance to D-cycloserine (DCS) was cloned from the chromosomal DNA of a DCS-producing Streptomyces garyphalus into Streptomyces lividans by a shot-gun cloning technique. Nucleotide sequence analysis revealed the existence of four open reading frames (ORFs B, C, D, and E), together with two incomplete ORFs, A and F. By introduction of the cloned fragment into Escherichia coli, the host obtained resistance to DCS. We showed that ORF B, which consists of 903 bp, is a DCS resistance gene. The hydropathy plot analysis of a protein deduced from ORF B revealed that the protein carries membrane-integral domains spanning the membrane 10 times, which suggests that the DCS-resistance determinant may be a factor associated with DCS transport.

Antibiotics, Antitubercular↗