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Curr Genet. 2000 Dec;38(5):233-40.

Alterations in the Saccharomyces MAL-activator cause constitutivity but can be suppressed by intragenic mutations.

Author information

1
Department of Biology, Queens College and the Graduate School of CUNY, Flushing, NY 11367, USA.

Abstract

The Saccharomyces MAL-activator regulates the maltose-inducible expression of the MAL structural genes encoding maltose permease and maltase. Constitutive MAL-activator mutant alleles of two types were identified. The first were truncation mutations deleting C-terminal residues 283-470 and the second contained a large number of alterations compared to inducible alleles scattered throughout the C-terminal 200 residues. We used site-directed in vitro mutagenesis of the inducible MAL63 and MAL63/23 genes to identify the residues responsible for the negative regulatory function of the C-terminal domain. Intragenic suppressors that restored the inducible phenotype to the constitutive mutants were identified at closely linked and more distant sites within the MAL-activator protein. MAL63/mal64 fusions of the truncated mutants suggest that residues in the N-terminal 100 residues containing the DNA-binding domain also modulate basal expression. Moreover, a transcription activator protein consisting of LexA(1-87)-Gal4(768-881)-Mal63(200-470) allowed constitutive reporter gene expression, suggesting that the C-terminal regulatory domain is not sufficient for maltose-inducible control of this heterologous activation domain. These results suggest that complex and very specific intramolecular protein-protein interactions regulate the MAL-activator.

PMID:
11191206
DOI:
10.1007/s002940000161
[Indexed for MEDLINE]

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