Ribosylurea Accumulates in Yeast urc4 Mutants

Abstract

Yeast Saccharomyces (Lachancea) kluyveri urc4 mutants, unable to grow on uracil, biotransformed ¹⁴C₂-uracil into two labeled compounds, as detected by high performance liquid chromatography (HPLC). These two compounds could also be obtained following organic synthesis of ribosylurea. This finding demonstrates that in the URC pyrimidine degradation pathway, the opening of the uracil ring takes place when uracil is attached to the ribose moiety. Ribosylurea has not been reported in the cell metabolism before and the two observed compounds likely represent an equilibrium mixture of the pyranosyl and furanosyl forms.

KEYWORDS:

• Uracil degradation
• ribosylurea
• URC pathway
• Saccharomyces (Lachancea) kluyveri

Acknowledgments

This work has been supported by the Swedish Research Council and Nilsson-Ehle Foundation.