antimony-potassium-tartrate and arsenic-acid

A glucantime sensitive Leishmania (V.) guyanensis strain was used to obtain in vitro resistant cell lines, by increments in glucantime concentrations employing both one step and stepwise protocols. Whereas the effective concentration of drug that inhibited the growth of wild type cells by 50% (EC50 value) was 0.20 mg Sb(v)/mL, the resistant cells were able to grow in glucantime concentrations greater than 8.0 mg/mL. The resistant cell lines were partially characterized by their in vitro response to glucantime, the stability of resistance phenotype, cross resistance to a range of drugs, and also by the analysis of total DNA fragments generated by restriction endonucleases and blot hybridization. Amplified DNA sequence similar to a P-glycoprotein analog from Leishmania tarentolae (ltpgpA gene) was observed in all the resistant cell lines obtained through the one-step protocol. These cell lines showed cross resistance to heavy metals but were sensitive to puromycin, vinblastine, and pentostam.

Topics: Animals; Antimony; Antimony Potassium Tartrate; Antimony Sodium Gluconate; Antiprotozoal Agents; Arsenates; ATP Binding Cassette Transporter, Subfamily B, Member 1; DNA, Protozoan; Drug Resistance; Drug Resistance, Multiple; Gene Dosage; Genes, Protozoan; Leishmania; Leishmania guyanensis; Meglumine; Meglumine Antimoniate; Organometallic Compounds; Oxides; Puromycin; Sequence Homology, Nucleic Acid; Vinblastine

The arsenate, arsenite, and antimonite resistance region of the Staphylococcus xylosus plasmid pSX267 was subcloned in Staphylococcus carnosus. The sequenced DNA region revealed three consecutive open reading frames, named arsR, arsB, and arsC. Expression studies in Escherichia coli with the bacteriophage T7 RNA polymerase-promoter system yielded three polypeptides with apparent molecular weights of 8,000, 35,000, and 15,000, which very likely correspond to ArsR, ArsB, and ArsC, respectively. ArsB was distinguished by its overall hydrophobic character, suggesting a membrane association. The arsenate, arsenite, and antimonite resistance was shown to be inducible by all three heavy metal ions. Inactivation of the first gene, arsR, resulted in constitutive expression of resistance. Similar results were obtained with transcriptional fusions of various portions of the ars genes with a lipase reporter gene, indicating a function of ArsR as a negative regulator of a putative promoter in front of arsR. The inactivation of arsR also resulted in reduction of resistance to arsenite and antimonite, while arsenate resistance was unaffected. The three ars genes conferred arsenite resistance in E. coli and arsenite as well as arsenate resistance in Bacillus subtilis.

Topics: Adenosine Triphosphatases; Amino Acid Sequence; Antimony; Antimony Potassium Tartrate; Arsenates; Arsenic; Arsenite Transporting ATPases; Arsenites; Bacillus subtilis; Bacterial Proteins; Base Sequence; Drug Resistance, Microbial; Escherichia coli; Escherichia coli Proteins; Gene Expression Regulation, Bacterial; Ion Pumps; Lipase; Molecular Sequence Data; Multienzyme Complexes; Operon; Promoter Regions, Genetic; Protein Conformation; R Factors; Staphylococcus; Trans-Activators; Transcription, Genetic