JOINT INFLUENCE OF red2 AND red3 MUTATIONS ON RIBOFLAVIN BIOSYNTHESIS
AND FERRIREDUCTASE ACTIVITY IN Pichia guilliermondii YEAST
K. Kapustyak, M. Stenchuk
Institute of cell biology, National Academy of Sciences of Ukraine,
Dragomanov st., 14/16, L'viv 79005, Ukraine,
e-mail: kapustyak@biochem.lviv.ua
In Pichia guilliermondii yeast, the riboflavin biosynthesis and iron transport are negatively regulated by RIB80, RIB81, HIT1 and RED1 genes. By using a new method of positive selection we isolated a collection of mutant strains representing 5 independent loci red2 through red6. In this study we report the investigation of two such mutations - red2 and red3. All of the mutant strains had significantly higher activity than WT ferric reductase. They also had increased levels of RF biosynthesis in the presence of iron and were hypersensitive to copper ions. We also demonstrated that red2 and red3 mutations were recessive, inherited in monogenic way and were not allelic to previously identified rib80, rib81, hit1 and red1 mutations with similar properties. Double mutants red2 red3 show additive interaction with respect to RF biosynthesis. From the results it is concluded that the novel genes RED2 and RED3 participate in the regulation of RF biosynthesis, as well as, in the regulation of iron assimilation in P. guilliermondii yeast.
Key words: yeast Pichia guilliermondii, riboflavin biosynthesis, regulatory genes.
|