A pattern of active accumulation of trehalose during growth on glucose medium, TAC(+) phenotype, is controlled by a polymeric series of maltose fermentation (MAL) genes. An essential requirement for expression of the TAC(+) phenotype is that the MAL gene be in the constitutive state, MAL (c). Mutation of a constitutive MAL allele to a maltose- inducible or nonfermenting (mal) state, alters the pattern of trehalose metabolism so that little or no trehalose accumulation occurs during growth on glucose medium. The TAC(+) phenotype is obtained in MAL (c) strains whether or not α-glucosidase formation is sensitive or resistant to carbon catabolite repression. However, trehalose accumulation is sensitive to glucose levels even in MAL (c) strains in which α-glucosidase formation is insensitive to catabolite repression. The effects of constitutive MAL genes on trehalose accumulation cannot be accounted for by an increase in trehalose-6 phosphate synthase or a decrease in trehalase as determined in vitro. A mechanism is proposed in which the gene-product of a MAL gene serves as a common positive regulator for expression of four genes coding respectively for maltose permease, maltase, α-methylglucosidase and a component of the trehalose accumulation system.

• PMID: 24190136
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Reference Type

Journal Article

Authors

de Oliveira DE, Rodrigues EG, Mattoon JR, Panek AD

Primary Lit For

MAL2 | MAL4 | MAL6

Additional Lit For

Review For