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PubMed2001

p-Aminobenzoic acid and chloramphenicol biosynthesis in Streptomyces venezuelae: gene sets for a key enzyme, 4-amino-4-deoxychorismate synthase.

Amplification of sequences from Streptomyces venezuelae ISP5230 genomic DNA using PCR with primers based on conserved prokaryotic pabB sequences gave two main products. One matched pabAB, a locus previously identified in S. venezuelae. The second closely resembled the conserved pabB sequence consensus and hybridized with a 3.8 kb NcoI fragment of S. venezuelae ISP5230 genomic DNA. Cloning and sequence analysis of the 3.8 kb fragment detected three ORFs, and their deduced amino acid sequences were used in BLAST searches of the GenBank database. The ORF1 product was similar to PabB in other bacteria and to the PabB domain encoded by S. venezuelae pabAB. The ORF2 product resembled PabA of other bacteria. ORF3 was incomplete; its deduced partial amino acid sequence placed it in the MocR group of GntR-type transcriptional regulators. Introducing vectors containing the 3.8 kb NcoI fragment of S. venezuelae DNA into pabA and pabB mutants of Escherichia coli, or into the Streptomyces lividans pab mutant JG10, enhanced sulfanilamide resistance in the host strains. The increased resistance was attributed to expression of the pair of discrete translationally coupled p-aminobenzoic acid biosynthesis genes (designated pabB/pabA) cloned in the 3.8 kb fragment. These represent a second set of genes encoding 4-amino-4-deoxychorismate synthase in S. venezuelae ISP5230. In contrast to the fused pabAB set previously isolated from this species, they do not participate in chloramphenicol biosynthesis, but like pabAB they can be disrupted without affecting growth on minimal medium. The gene disruption results suggest that S. venezuelae may have a third set of genes encoding PABA synthase.

4-Aminobenzoic Acid↗

PubMed1990

Mass Spectrometric Measurement of Intracellular Carbonic Anhydrase Activity in High and Low C(i) Cells of Chlamydomonas: Studies Using O Exchange with C/O Labeled Bicarbonate.

By measuring (18)O exchange from doubly labeled CO(2) ((13)C(18)O(18)O), intracellular carbonic anhydrase activity was studied with protoplasts and chloroplasts isolated from Chlamydomonas reinhardtii grown either on air (low inorganic carbon [C(i)]) or air enriched with 5% CO(2) (high C(i)). Intact low C(i) protoplasts had a 10-fold higher carbonic anhydrase activity than did high C(i) protoplasts. Application of dextran-bound inhibitor and quaternary ammonium sulfanilamide, both known as membrane impermeable inhibitors of carbonic anhydrase, had no influence on the catalysis of (18)O exchange, indicating that cross-contamination with extracellular carbonic anhydrase was not responsible for the observed activity. This intracellular in vivo activity from protoplasts was inhibited by acetazolamide and ethoxyzolamide. Intracellular carbonic anhydrase activity was partly associated with intact chloroplasts isolated from high and low C(i) cells, and the latter had a sixfold greater rate of catalysis. The presence of dextran-bound inhibitor had no effect on chloroplast-associated carbonic anhydrase, whereas 150 micromolar ethoxyzolamide caused a 61 to 67% inhibition of activity. These results indicate that chloroplastic carbonic anhydrase was located within the plastid and that it was relatively insensitive to ethoxyzolamide. Carbonic anhydrase activity in crude homogenates of protoplasts and chloroplasts was about six times higher in the low C(i) than in high C(i) preparations. Further separation into soluble and insoluble fractions together with inhibitor studies revealed that there are at least two different forms of intracellular carbonic anhydrase. One enzyme, which was rather insoluble and relatively insensitive to ethoxyzolamide, is likely an intrachloroplastic carbonic anhydrase. The second carbonic anhydrase, which was soluble and sensitive to ethoxyzolamide, is most probably located in an extrachloroplastic compartment.

Journal Article↗

PubMed1982

Conjugation of drug-resistance plasmids from vibrio anguillarum to Vibrio parahaemolyticus.

Drug-resistant strains of Vibrio anguillarum, a fish pathogen, were isolated from diseased fish in culture ponds. In investigations of these strains, the transfer of resistance to chloramphenicol, tetracycline, and sulfanilamide from multiple resistant organisms to laboratory recipients was observed. The plasmid from V. anguillarum was stably maintained in both recipient strains of Vibrio parahaemolyticus and Escherichia coli. The plasmids isolated from Vibrio anguillarum belong to incompatibility group C. The molecular weight of these plasmids determined by electron microscopic observation was about 103 to 113 megadaltons.

Chloramphenicol↗

PubMed1983

Conjugal transferability of multiple resistance in Shigella strains.

Shigella strains isolated in Japan between 1971 and 1979 were surveyed for drug resistance and distribution of R plasmids. Of 2,510 strains, 89.3% were resistant to either one or various combinations of four drugs, tetracycline, chloramphenicol, streptomycin, and sulfanilamide. About 66% of the Shigella isolates were quadruply resistant. The frequency of isolation of R plasmids from quadruply resistant Shigella strains was the highest when compared with other strains resistant to various combinations of the four drugs. The conjugal transferability of 204 quadruply resistant strains isolated between 1977 and 1979 was tested by various mixed-culture methods. Among the total strains examined, 70.6% carried transferable resistance when tested by the conventional broth culture method, 90.2% transferred their resistance when, in addition the replica-plating method was used and 97.5% could transfer their resistance when the membrane filter method was also used. Although the remaining five strains could not transfer their resistance by any of the mixed culture methods, the drug resistance of four of the five strains was mobilized by the concomitant presence of F-tet or T-kan plasmid. These results indicate that almost all of the quadruple resistance in Shigella isolates was mediated by plasmid.

Conjugation, Genetic↗

PubMed1983

Incompatibility group K plasmids in bacteria isolated from a urinary tract infection.

Citrobacter freundii and Klebsiella pneumoniae were concurrently isolated from a patient with a urinary tract infection. Transferable drug resistant plasmids were isolated from both strains, pMS434 and pMS435. These plasmids belonged to incompatibility group K and both carried genes governing resistance to various aminoglycoside antibiotics, i.e., kanamycin, gentamicin C complex, streptomycin, and 3',4'-dideoxykanamycin B, in addition to those governing resistance to sulfanilamide and ampicillin. They inactivated kanamycin, gentamicin C complex and 3',4'-dideoxykanamycin by adenylylation and kanamycin by phosphorylation. Electron microscopic observations disclosed that the molecular weights of the plasmids were about 67.8 megadaltons. These results indicated the similarity in genetic constitution of the two plasmids. This was the second isolation of incompatibility group K plasmids, following that reported by Hedges and Datta (Nature 234: 220-221, 1971).

Aminoglycosides↗

PubMed2006

Evidence for folate-salvage reactions in plants.

Folates in vivo undergo oxidative cleavage, giving pterin and p-aminobenzoylglutamate (pABAGlu) moieties. These breakdown products are excreted in animals, but their fate is unclear in microorganisms and unknown in plants. As indirect evidence from this and previous studies strongly suggests that plants can have high folate-breakdown rates (approximately 10% per day), salvage of the cleavage products seems likely. Four sets of observations support this possibility. First, cleavage products do not normally accumulate: pools of pABAGlu (including its polyglutamyl forms) are equivalent to, at most, 4-14% of typical total folate pools in Arabidopsis thaliana, Lycopersicon esculentum and Pisum sativum tissues. Pools of the pterin oxidation end-product pterin-6-carboxylate are, likewise, fairly small (3-37%) relative to total folate pools. Second, little pABAGlu built up in A. thaliana plantlets when net folate breakdown was induced by blocking folate synthesis with sulfanilamide. Third, A. thaliana and L. esculentum tissues readily converted supplied breakdown products to folate synthesis precursors: pABAGlu was hydrolysed to p-aminobenzoate and glutamate, and dihydropterin-6-aldehyde was reduced to 6-hydroxymethyldihydropterin. Fourth, both these reactions were detected in vitro; the reduction used NADPH as cofactor. An alternative salvage route for pABAGlu, direct reincorporation into dihydrofolate via the action of dihydropteroate synthase, appears implausible from the properties of this enzyme. We conclude that plants are excellent organisms in which to explore the biochemistry of folate salvage.

Arabidopsis↗

PubMed1975

Human renal carbonic anhydrase. Purification and properties.

Carbonic ahyndrase was isolated from fresh human donor kidneys which had been thoroughly perfused free from blood. The isolation procedure involved biospecific affinity chromatography on a sulfanilamide-agarose column and yielded one soluble form of the enzyme, which was homogenous with respect to sedimentation in the ultracentrifuge, electrophoresis, isoelectric focusing and immunodiffusion. The renal enzyme had an amino acid composition and beahved chromatographically, electrophoretically, and immunochemically like the erythrocyte form human carbonic anhydrase C, isolated by the same technique. The kinetic behaviour of the renal enzyme was similar to that of human carbonic anhydrase C when compared by the stopped-flow pH-indicator technique. The results therefore suggest that the cytoplasmic carbonic anhydrase of the human kidney is very similar, if not identical, to the high-activity erythrocyte form of human carbonic anhydrase C.

Amino Acids↗

PubMed1980

Human renal cytoplasmic carbonic anhydrase. Tissue levels and kinetic properties under near physiological conditions.

The cytoplasmic form of human renal carbonic anhydrase, CA-C (carbonate dehydratase, EC 4.2.1.1), purified by affinity chromatography, was characterized kinetically at 37 degrees C in 25 mM N-methyl imidazole buffer, I = 0.15, pH 7.1. using a pH-indicator stopped-flow technique. Under these conditions the rate constants for the uncatalyzed hydration of CO2 and dehydration of H2CO3 were 0.12 . s-1 and 0.60 . s-1, respectively. The kinetic parameters for CA-C were found to be: Hydration reaction, Km = 11.8 mM, V/[E]0 = 10.6 x 10(5) . s-1, dehydration reaction Km = 70 mM, V/[E]0 = 5 x 10(5) . s-1. In the hydration reaction CA-C was non-competitively inhibited by acetazolamide, Ki = 16 nM, sulfanilamide, Ki = 8 micrometer, and chlorothiazide, Ki = 1 micrometer. The levels of immunoassayable CA-C in cortex, medulla and papilla of perfused donor kidneys were 1.3, 1.0 and 0.6 mg enzyme protein/g tissue protein respectively which corresponded well with the levels measured catalytically. The erythrocyte form, HCA-B, was also detected immunochemically (approximately 0.1 mg/g protein) but is thought to be a contaminant. Calculations indicated that the uncatalyzed hydration of CO2 in the tubular cells can support 17 or 0.7% of the rate of urine acidification, dependent on whether the cellular alkaline pH-disequilibrium during acid secretion is 0.1 or 0.01 pH units, respectively. CA-C accelerates the hydration rate 6800-fold which enables the cell to sustain high rates of proton generation, while maintaining near CO2-equilibrium and maximal buffering capacity. Even at an assumed pH-disequilibrium of only 0.01 pH-unit, CA-C is present in 50-fold excess of apparent physiological needs. When the enzyme is inhibited the rate of the uncatalyzed reaction increases, which partly overcomes the effect of inhibition.

Carbonic Anhydrases↗

PubMed1989

[Drug-resistance and its transferability of Shigella strains isolated in 1986 in Japan].

Two hundred and fifty Shigella strains isolated in Japan were examined for their drug-resistances and their conjugal transferability. Drugs used and the isolation frequency of resistant strains were: sulfanilamide (SA) 96%, streptomycin (SM) 85%, tetracycline (TC) 82%, fosfomycin (FOM) 76%, chloramphenicol (CP) 51%, trimethoprim (TMP) 46%, ampicillin (ABPC) 45%, nalidixic acid (NA) 6%, kanamycin (KM) 5%, cephaloridine (CER) 4%, gentamicin (GM) 0%, amikacin (AMK) 0%, colistin (CL) 0%, norfloxacin (NFLX) 0%. All of the KM-resistances and none of the FOM-resistances were transferable. Each 20 to 30% of CP, TC, SM, SA or ABPC-resistant isolates transferred each drug-resistance. Two thirds of the isolates were brought to Japan by travellers mostly from South-East Asia. The isolation frequency of resistant strains was not different between domestic and foreign strains except that NA-resistance was not found in foreign strains. The frequency of isolates carrying transferable R plasmids were higher in domestic strains than foreign strains. Most of the isolated had multiple drug-resistance. Major resistance types were: (CP, TC, SM, SA, ABPC) 22%; (TC, SM, SA, TMP) 20%; (CP, TC, SM, SA, ABPC, TMP) 16%; (TC, SM, SA) 8%. Strains showing different resistance types were different among each other in their serum type, conjugal transferability, and derived country. Stepwise evolution of multiple resistance in one country was not demonstrated. The resistance types of Shigella isolates in Japan have been influenced by yearly change of imported strains.

Anti-Bacterial Agents↗

PubMed1978

Streptomycin and Spectinomycin resistance mediated by plasmids.

Resistance to tetracycline (Tc), chloramphenicol (Cm), streptomycin (Sm), and sulfanilamide (Sa) was surveyed in clinical isolates of Escherichia coli and Shigella strains. Among the Sm Sa-resistant strains, the frequency of nonconjugative r (Sm Sa) plasmids was much higher than that of conjugative R plasmids encoding double resistance. The biochemical mechanism of Sm resistance mediated by the conjugative plasmids R(Tc Cm Sm Sa) and R(Cm Sm Sa) and about half the numbers of conjugative R(Tc Sm Sa) and R(Sm Sa) plasmids tested were found to be due to adenylylation of the drug. The remaining conjugative R(Tc Sm Sa) and R(Sm Sa) plasmids and all nonconjugative (Sm Sa) plasmids tested inactivated Sm by phosphorylation.

Conjugation, Genetic↗

PubMed1996

Monodrug efficacies of sulfonamides in prophylaxis for Pneumocystis carinii pneumonia.

A remarkably high rate of adverse events is associated with the use of trimethoprim-sulfamethoxazole in patients with human immunodeficiency virus type 1 infection. We examined the efficacies of sulfonamides alone in the prevention of Pneumocystis carinii pneumonitis, with the assumption that at least some of the adverse events with the drug combination might be due to trimethoprim. With the immunosuppressed rat model, eight sulfonamides were studied at 100, 10, and 1.0 mg/kg/day (10 rats per dosage and drug). P. carinii infection was prevented in all animals (100%) receiving dosages of as little as 1.0 mg of sulfamethoxazole, sulfamethoxypyridazine, and sulfadimethoxine per kg per day, as little as 10 mg of sulfameter, sulfachlorpyridazine, and sulfaquinoxaline per kg per day; and 100 mg of sulfaguanidine and sulfanilamide per kg per day. These studies suggest that a sulfonamide, such as sulfamethoxazole, might provide effective prophylaxis for P. carinii pneumonitis without trimethoprim.

Animals↗

PubMed1998

Quantitative structure-activity relationship studies of a series of sulfa drugs as inhibitors of Pneumocystis carinii dihydropteroate synthetase.

Sulfone and sulfanilamide sulfa drugs have been shown to inhibit dihydropteroate synthetase (DHPS) isolated from Pneumocystis carinii. In order to develop a pharmacophoric model for this inhibition, quantitative structure-activity relationships (QSAR) for sulfa drugs active against DHPS have been studied. Accurate 50% inhibitory concentrations were collected for 44 analogs, and other parameters, such as partition coefficients and molar refractivity, were calculated. Conventional multiple regression analysis of these data did not provide acceptable QSAR. However, three-dimensional QSAR provided by comparative molecular field analysis did give excellent results. Upon removal of poorly correlated analogs, a data set of 36 analogs, all having a common NHSO2 group, provided a cross-validated r2 value of 0.699 and conventional r2 value of 0.964. The resulting pharmacophore model should be useful for understanding and predicting the binding of DHPS by new sulfa drugs.

Dihydropteroate Synthase↗

PubMed1974

Demonstration of R factors from Pseudomonas aeruginosa.

Sixty strains of Pseudomonas aeruginosa were selected from our clinical stock cultures and used as donors of drug resistance to examine the presence of R factors. They were highly resistant to one or more of six drugs including tetracycline (TC), chloramphenicol (CM), streptomycin (SM), sulfanilamide (SA), carbenicillin (CPC), and kanamycin (KM). Three FP(-), auxotrophic mutants of P. aeruginosa were used as recipients, which had been made resistant to either rifampin (RMP) or KM by in vitro mutation. Each donor was mated with each of the three recipients, and 45 strains were found to transfer their resistance to one or more recipients. A second series of conjugation experiments using 45 exconjugants as donors showed that 23 could transfer their resistance. We conclude that these strains carry R factors that are transmissible to one or more recipients. Eleven carried resistance to (TC.CM.SM.SA.CPC), nine to (TC.CM.SM.SA), one to (TC.CM.SA.CPC), one to (TC.CM.SA), and one to (SM). All of these R factors could not be transmitted to other species belonging to the family Enterobacteriaceae.

Anti-Bacterial Agents↗

PubMed1974

New antimicrobial nitrofuran, trans-5-amino-3-[2-(5-nitro-2-furyl)vinyl]-delta2-1,2,4-oxadiazole: antimicrobial efficacy in mice, rats, and guinea pigs.

A new antimicrobial nitrofuran designated SQ 18,506 showed some therapeutic activity when administered orally to mice infected with Escherichia coli, Salmonella schottmuelleri, Shigella flexneri, or Klebsiella pneumoniae. Animals infected parenterally with Streptococcus pyogenes, Proteus mirabilis, Mycobacterium tuberculosis, and Candida albicans, or topically with Trichophyton mentagrophytes, did not respond to therapy with the drug at the dosage levels used. The compound was as effective as metronidazole in the topical treatment of experimental trichomonal infections in mice and in guinea pigs and as effective as nystatin, candicidin, or a sulfanilamide-aminacrine hydrochloride cream in the treatment of a candidal vaginal infection in rats. The chemotherapeutic efficacy of SQ 18,506 in experimental vaginitis caused by Escherichia coli in the rat surpassed that shown by four commercial products available for the treatment of bacterial vaginitis.

5-Amino-3-((5-nitro-2-furyl)vinyl)-1,2,4-oxadiazol↗

PubMed1975

Acetylation of amikacin, a new semisynthetic antibiotic, by Pseudomonas aeruginosa carrying an R factor.

A clinical isolate Pseudomonas aeruginosa GN315 resistant to amikacin (AK), a new semisynthetic antibiotic, inactivated AK by acetylation. The acetylating enzyme was purified approximately 146-fold from a crude extract of GN315 by affinity chromatography. Fractionated samples obtained by affinity chromatography showed almost the same inactivation curves toward 3',4'-dideoxykanamycin B (DKB) and AK. Partially purified AK-acetylating enzyme inactivated DKB and kanamycin A but could not inactivate gentamicin C(1). The optimal pH for their inactivation was 6.0 to 7.0, and the pH curves for the inactivation of both drugs were almost the same. These facts indicate that AK and DKB are inactivated by the same aminoglycoside-acetylating enzyme. Through elemental analysis, the inactivated AK was found to be a monoacetylated product of AK. A sample of inactivated AK was purified and compared with a synthetic 6'-N-acetyl AK by thin-layer chromatography, and the results indicated that AK was inactivated by acetylation of the 6'-NH(2) group. The ultraviolet, infrared, and nuclear magnetic resonance spectra of the inactivated AK showed that AK was inactivated by the enzyme through acetylation of the amino group of 6'-amino-6'-deoxy-d-glucose moiety of AK. This enzyme, mediated by R factor, is capable of conferring resistance to AK, DKB, kanamycin, gentamicin, and sulfanilamide.

Aminoglycosides↗

PubMed1975

Structure-activity of sulfones and sulfonamides on dihydropteroate synthetase from Neisseria meingitidis.

The molecular interaction of various sulfones and sulfonamides with partially purified dihydropteroate synthetase from Neisseria meningitidis M-166 has been examined. The mode of action of the sulfones was similar to that of the sulfonamides. Both groups of drugs were competitive inhibitors of dihydropteroate synthetase with respect to p-aminobenzoate in a partially purified enzyme preparation. 4,4'-Diaminodiphenylsulfone was three times more effective than sulfadiazine and nine times more effective than sulfanilamide as a competitive inhibitor of dihydropteroate synthetase. The inhibitory activity of 4-amino-4'-acetamidodiphenylsulfone and 4-amino-4'-formamidodiphenylsulfone in this system eliminated their prior conversion to 4,4'-diaminodiphenylsulfone as a requirement for activity.

Dihydropteroate Synthase↗

PubMed1976

Drug resistance and distribution of R factors in Salmonella strains.

Drug resistance and the distribution of R factors in Salmonella strains were surveyed using 1,980 strains isolated in Japan from 1955 to 1973. Resistances were mostly restricted to sulfanilamide (SA), tetracycline (TC), and streptomycin (SM), and combinations thereof. The demonstrated frequency of strains resistant to chloramphenicol (CM) was very low as compared with that in Escherichia coli and Shigella strains. In relation to resistance to TC, CM, SM and SA, the frequency of isolation of single resistance was the highest, followed by triple, double, and quadruple resistance in that order. Low frequency of isolation of quadruple resistance was due to the low frequency of CM resistance in Salmonella strains and differed from the E. coli or Shigella group. R factors with single TC resistance was most common, followed by those with TC,SM,SA; SM,SA; TC,CM,SM,SA; and single (SM and SA) resistance, in that order. Kanamycin and ampicillin resistance was unusual and mostly transmissible.

Anti-Bacterial Agents↗

PubMed1976

Observations on brilliant green agar with H2S indicator.

Several formulations of brilliant green agar with an added H2S indicator were evaluated. Results were optimum with variations of a basic formula consisting of 40 g of tryptic soy agar (Difco), 8 g of lactose, 8 g of sucrose, 80 mg of phenol red, 1 g of sulfanilamide, 1.5 g of ferric ammonium citrate, 5 g of sodium thiosulfate pentahydrate, and 7 mg of brilliant green dye per liter. Brilliant green dye was added after sterilization of the other components This formulation supported good growth of all of 39 strains of Salmonella tested. Normal biochemical types formed pink colonies with black centers, and an H2S-negative S. choleraesuis formed pink colonies without black centers. Of other bacteria tested, only Enterobacter, Klebsiella, and a few Citrobacter strains showed significant growth in 24 h. When lactose was omitted from the formulation, a lactose-fermenting strain formed pink colonies with black centers, and differentiation of Salmonella from the Enterobacter-Klebsiella groups was equally good. Addition of xylose (4.0 g) and L-lysine hydrochloride (5.4 g) to the above formulation improved differentiation between Salmonella and the few Citrobacter strains that grew and produced more intense blackening in Salmonella colonies. Addition of an H2S indicator to brilliant green agar formulations aided in identification of Salmonella colonies, especially in mixtures with other bacteria. These media were judged to give better differentiation of salmonellae from other bacteria than Hektoen agar with added novobiocin (10 mg/liter).

Agar↗