Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.5.4.1 (cytosine deaminase)
 747 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Mutants resistant to 5-fluorouracil, 5-fluorocytosine, and 5-fluorouridine were selected in yeast, and the mechanisms of their resistance were investigated. The investigated mutations map in seven different loci. (i) A mutation at the locus FUI 1 gives specifically resistance to 5-fluorouridine. (ii) Two loci are involved in a specific 5-fluorocytosine resistance: a mutation at locus FCY 1 produces a loss of cytosine deaminase activity; a mutation at locus FCY 2 results in the loss of the activity of a cytosine-specific permease. (iii) A mutation at the locus FUR 4 gives a simultaneous resistance to 5-fluorouracil and to 5-fluorouridine by loss in the activity of the uracil-specific permease. (iv) We found three types of mutants in the locus FUR 1. One is dominant and weakly resistant to 5-fluorouracil, 5-fluorocytosine, and 5-fluorouridine. The two others are recessive and are unable to catalyze one of the steps involved in uracil transformation into uridine 5'-monophosphate; this block-age explains their strong resistance to 5-fluorouracil and 5-fluorocytosine. Of these two mutants, one is resistant to 5-fluorouridine and the other is not. (v) Mutations at locus FUR 2 give resistance to 5-fluorouracil, 5-fluorocytosine, and 5-fluorouridine. These mutations are dominant and lead to a loss in the feedback regulation of the aspartic transcarbamylase activity by uridine triphosphate. (vi) The mutants FUR 3 are resistant to 5-fluorocytosine and 5-fluorouridine. They are dominant and physiologically related to the mutants of the locus FUR 1 but their mechanism of resistance is not understood.
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PMID:Genetic and physiological aspects of resistance to 5-fluoropyrimidines in Saccharomyces cerevisiae. 542 21

Pyrimidine synthesis in the food spoilage agent Burkholderia cepacia ATCC 25416 was investigated. The five de novo pathway enzymes of pyrimidine biosynthesis were found to be active in B. cepacia ATCC 25416 and growth of this strain on uracil had an effect on the de novo enzyme activities. The in vitro regulation of aspartate transcarbamoylase activity in B. cepacia ATCC 25416 was studies and its activity was inhibited by PP(i), ATP, GTP, CTP and UTP. The enzymes cytidine deaminase, uridine phosphorylase and cytosine deaminase were found to be active in the salvage of pyrimidines in ATCC 25416. Overall, de novo pyrimidine synthesis in B. cepacia ATCC 25416 was regulated at the level of enzyme activity and its pyrimidine salvage enzymes differed from those found in B. cepacia ATCC 17759.
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PMID:Pyrimidine synthesis in Burkholderia cepacia ATCC 25416. 757 30