Insertion of non-homologous DNA sequences into a regulatory gene cause a constitutive maltase synthesis in yeast
✍ Scribed by Rosaura Rodicio
- Book ID
- 104768797
- Publisher
- Springer-Verlag
- Year
- 1986
- Tongue
- English
- Weight
- 708 KB
- Volume
- 11
- Category
- Article
- ISSN
- 0172-8083
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✦ Synopsis
Two maltase constitutive alleles MALl-1 c and MALl-2 c were obtained as revertants from a defective mall-1 mutant allele not promoting maltose fermentation. Classical genetical analysis showed that the mutations were linked or allelic to the MALl locus. Dominance relations were established by testing a-glucosidase activities in diploids containing various allele combinations.
The maltose regulatory genes belonging to the MALl, MALl-1 c and MALl-2 c alleles were cloned. Differences in restriction sites were found between the wild type MALl and the derived MALl-constitutive alleles. The MALl regulatory gene was located in a 1.15 kb EcoRI fragment (Rodicio and Zimmermann 1985a, b). An EcoRI fragment of this size was found in plasmids containing the MALl regulatory wild type allele but was absent from plasmids carrying the constitutive alleles.
The genomic organization of the MAL loci in the constitutive mutants was confirmed by Southern analysis. Various fragments containing sequences of the different MALl alleles were used to probe genomic digests of MALl, MALl-1 c and MALl-2 c strains. The results obtained support the conclusion that the constitutive mutations had arisen by a rearrangement between the original mall-1 mutant allele and sequences with different location in the genome.