A constitutive thiamine metabolism mutation, thi80, causing reduced thiamine pyrophosphokinase activity in Saccharomyces cerevisiae.
AUTOR(ES)
Nishimura, H
RESUMO
We identified a strain carrying a recessive constitutive mutation (thi80-1) with an altered thiamine transport system, thiamine-repressible acid phosphatase, and several enzymes of thiamine synthesis from 2-methyl-4-amino-5-hydroxymethylpyrimidine and 4-methyl-5-beta-hydroxyethylthiazole. The mutant shows markedly reduced activity of thiamine pyrophosphokinase (EC 2.7.6.2) and high resistance to oxythiamine, a thiamine antagonist whose potency depends on thiamine pyrophosphokinase activity. The intracellular thiamine pyrophosphate content of the mutant cells grown with exogenous thiamine (2 x 10(-7) M) was found to be about half that of the wild-type strain under the same conditions. These results suggest that the utilization and synthesis of thiamine in Saccharomyces cerevisiae is controlled negatively by the intracellular thiamine pyrophosphate level.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=207844Documentos Relacionados
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