Biopolymers and cell. 1999; 15 (6): 522 - 528

A novel gene RED1, which controls riboflavin biosynthesis and ferrireductase activity in Picliia guilliermondii yeast

N. N. Stenchuk, K. E. Kapustiak

The red/ mutant of Pichia guilliermondii yeast with high reducing activity for threephenyltetrasolium chloride (TTC) has been selected using solid synthetic medium with TTC. The data obtained demon¬strate several p/ienotypes of mutant cells with: a) increased level of riboflavin biosynthesis, b) enhanced ferrireductase and GTP-cyclo-hydrolase activity, c) higher non-hem in iron content, d) hyper-sensitivity to copper. All these properties are defined by one mutant allele red. Genetic studies indicated that red! is not allelic to previously identified hit I, ribSO and ribSI mutations with similar properties, in the double mutant redl and ribtil, the production of riboflavin and the expression of GTP-cyclo/iydrolase is increased drastically, i. e. two genes act synergetically. Thus, the novel gene RED1 participates in the regulation of both riboflavin biosynthesis and ferrireductase activity. It is tempting to speculate this gene is involved in the iron and copper transport in Pichia gu.illiermond.il ye ant.