MAL64c is a global regulator of alpha-glucoside fermentation: identification of a new gene involved in melezitose fermentation.

Maltase constitutive mutants at the MAL6 locus have been mapped to the newly identified regulatory gene MAL64c. We show here that MAL64c has in addition pleiotropic effects on sugar fermentation: MAL64c strains constitutively synthesize an alpha-methylglucosidase and can complement a new gene, MTP1, for the fermentation of melezitose and alpha-methylglucoside. MTP1, maps near MAL1, and either encodes a permease which transports melezitose, alpha-methylglucoside, and maltose or regulates the activity of such a permease. This work shows that MAL64c, a trans-acting regulatory gene, is a global regulatory gene affecting several different pathways of alpha-glucoside metabolism.