ISSN:
1432-0983
Keywords:
Key words Pyrimidine salvage pathway
;
Cytidine deaminase
;
Cytidine metabolism
;
CDD1
;
Uridine/cytidine kinase
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
Notes:
Abstract Cytidine metabolism in the yeast Saccharomyces cerevisiae was analyzed by genetic and biochemical approaches. Disruption of a unique ORF (Genbank accession No. U 20865) bearing homology with eucaryotic or bacterial cytidine deaminases abolished cytidine deaminase activity and resulted in 5-fluorocytidine resistance. The gene encoding cytidine deaminase will be referred to as CDD1 (Genbank accession number AF080089). The ability to isolate mutants resistant to 5-fluorocytidine which mapped to five other loci demonstrated the existence of a complex cytidine metabolic network. Deciphering this network revealed several original features: (1) cytidine entry is mediated by the purine-cytosine transporter (Fcy2p), (2) cytidine is cleaved into cytosine by the uridine nucleosidase (Urh1p), (3) cytidine is phosphorylated into CMP by the uridine kinase (Urk1p), (4) a block in cytosine deaminase (Fcy1p), but not in cytidine deaminase (Cdd1p), constitutes a limiting step in cytidine utilisation as a UMP precursor.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/s002940050482
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