Methylthioadenosine and polyamine biosynthesis in a Saccharomyces cerevisiae meu1delta mutant

As part of our studies on polyamine biosynthesis in yeast, the metabolism of methylthioadenosine was studied in a mutant that lacks methylthioadenosine phosphorylase (meu1delta). The nucleoside accumulates in this mutant and is mainly excreted into the culture medium. Intracellular accumulation of t...

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Bibliographic Details
Published in:Biochemical and biophysical research communications 2006-04, Vol.343 (1), p.203-207
Main Authors: Chattopadhyay, Manas K, Tabor, Celia White, Tabor, Herbert
Format: Article
Language:English
Subjects:
Adenosine - analogs & derivatives
Adenosine - biosynthesis
Gene Deletion
Methionine - metabolism
Mutation
Purine-Nucleoside Phosphorylase - genetics
Saccharomyces cerevisiae - genetics
Saccharomyces cerevisiae - metabolism
Saccharomyces cerevisiae Proteins - genetics
Spermidine - biosynthesis
Spermine - biosynthesis
Thionucleosides - biosynthesis
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Summary:As part of our studies on polyamine biosynthesis in yeast, the metabolism of methylthioadenosine was studied in a mutant that lacks methylthioadenosine phosphorylase (meu1delta). The nucleoside accumulates in this mutant and is mainly excreted into the culture medium. Intracellular accumulation of the nucleoside is enough to account for the inhibition of spermidine synthase and thus to indirectly regulate the polyamine content of the meu1delta cells. By comparing the results with this mutant with a meu1delta spe2delta mutant that cannot synthesize spermidine or spermine, we showed that >98% of methylthioadenosine is produced as a byproduct of polyamine synthesis (i.e., from decarboxylated S-adenosylmethionine). In contrast, in MEU1+ SPE2+ cells methylthioadenosine does not accumulate and is metabolized through the methionine salvage pathway. Using a met15delta mutant we show that this pathway (i.e., involving polyamine biosynthesis and methylthioadenosine metabolism) is a significant factor in the metabolism of methionine, accounting for 15% of the added methionine.
ISSN:0006-291X