A REGULATORY MUTANT OF HANSENULA-POLYMORPHA EXHIBITING METHANOL UTILIZATION METABOLISM AND PEROXISOME PROLIFERATION IN GLUCOSE

Mutant LGM-128 of Hansenula polymorpha harbors the recessive mutation glr2-1 which confers a complex pleiotropic phenotype, the major featur e of which is the metabolically unnecessary induction of methanol util ization metabolism (C-1 metabolism) during growth on glucose, whether or not methanol is in the medium. Therefore, in this mutant, peroxisom es are formed and proliferate upon cultivation in glucose-containing m edia. In these media, LGM-128 shows induction levels of C-1 metabolism that are similar to those observed in methanol-containing media. This indicates that GLR2 controls the repression derepression process stim ulated by glucose and that the induction process triggered by methanol plays only a minor role in activating C-1 metabolism. Cultivating LGM -128 in methanol and then transferring it to glucose media revealed th at active degradative processes occur, leading to the disappearance of C, metabolism. This observation suggests that, although stimulated by glucose, the two processes are controlled by elements which are, at l east in part, distinct. Finally, glr2-1 does not affect ethanol repres sion, suggesting that in H. polymorpha the two repressing circuits are separated.