Metabolism of ethionine in ethionine-sensitive and ethionine-resistant cells of the enteric yeast Candida slooffii.
In a defined medium with added ethionine plus low methionine, phenylalanine, tryptophan, tyrosine, adenine, and additional methionine reversed inhibition of the enteric yeast Candida slooffii by ethionine. Isoleucine and 7-methylguanine restored half-maximal growth. Choline but not triethylcholine inhibited C. slooffii. 6-Mercaptopurine reversed ethionine inhibition and also synergistic inhibition by ethionine plus choline. Protection against ethionine by adenine plus aromatics was also evident with log-phase cells in the absence of methionine. Incorporation of ethionine-ethyl-1-(14)C by resting cells was partially inhibited by aromatic amino acids and methionine. Ethionine depressed incorporation of (3)H-phenylalanine but not of (3)H-adenine. Ethionine-resistant mutants were isolated which incorporated ethionine efficiently and degraded it to yet unidentified substances not including 5'-ethylthioadenosine. Ethionine-sensitive cells accumulated more S-adenosylethionine (SAE) than resistant mutants. Adenine was a good precursor of SAE. Radioactivity from ethionine-ethyl-1-(14)C was recovered from cell fractions of ethionine-sensitive cells with the following distribution: cold trichloroacetic acid-soluble > hot trichloroacetic acid-insoluble > lipids > deoxyribonucleic acid > ribonucleic acid. Total radioactivity recovered from ethionine-sensitive cells was twice as much as that from ethionine-resistant mutants.
D000225:Adenine / Q000378:metabolism; D000596:Amino Acids / Q000494:pharmacology; D002175:Candida / Q000187:drug effects / Q000254:growth & development / Q000378:metabolism*; D002247:Carbon Isotopes; D002458:Cell Fractionation; D002794:Choline / Q000494:pharmacology; D002854:Chromatography, Paper; D003470:Culture Media; D003864:Depression, Chemical; D004352:Drug Resistance, Microbial; D005001:Ethionine / Q000378:metabolism* / Q000494:pharmacology; D005827:Genetics, Microbial; D015122:Mercaptopurine / Q000494:pharmacology; D008715:Methionine / Q000378:metabolism; D009154:Mutation; D010649:Phenylalanine / Q000378:metabolism; D011687:Purines / Q000494:pharmacology; D011743:Pyrimidines / Q000494:pharmacology; D013237:Stereoisomerism; D014316:Tritium
D000596:Amino Acids; D002247:Carbon Isotopes; D003470:Culture Media; D011687:Purines; D011743:Pyrimidines; D014316:Tritium; D010649:Phenylalanine; D008715:Methionine; D015122:Mercaptopurine; D000225:Adenine; D002794:Choline; D005001:Ethionine