[Cloning of the RIB1 gene coding for the enzyme of the first stage of flavinogenesis in the yeast Pichia guilliermondi, GTP cyclohydrolase, in Escherichia coli cells].

The RIB1 gene encoding the enzyme of the first stage of the yeast Pichia guillermondii-GTP-cyclohydrolase- was cloned on pFL38 shuttle vector as the Sau3A fragment of chromosomal DNA of about 9 kb. EcoRI fragment of 4 kb with RIB1 gene was subcloned from the pFRI hybrid plasmid obtained into the pUC18 plasmid and then shortened to give 2.9 kb via deletion in SalGI site. The plasmid constructed was designated pR1. Activity of GTP-cyclohydrolase was 80-100-fold higher in extracts of transformants than in the prototroph strain, which evidence of effective expression of the yeast gene within recombinant plasmids in the cells of this species of bacteria. The enzyme isolated from transformants has molecular mass 179 kDa, is inhibited by PAD and adenyl-nucleotides, which is characteristic of GTP-cyclohydrolase of P. guilliermondii but not of Escherichia coli.