Isolation and Characterization of Sge1: A Yeast Gene That Partially Suppresses the Gal11 Mutation in Multiple Copies

AUTOR(ES)

Amakasu, H.

RESUMO

Recessive mutations of GAL11 in Saccharomyces cerevisiae cause pleiotropic defects that include weak fermentation of galactose, α-specific sterility and slow growth on nonfermentable carbon sources. Recent experiments suggest that Gal11p functions as a ``coactivator'' that links transcriptional activators, such as Gal4p and Grf1p/Rap1p/Tuf1p, with the basic transcription machinery. In the present experiments we isolated a gene, SGE1, that suppresses gal11 for growth on ethidium bromide/galactose agar when the gene was present in two or more copies. The other gal11 phenotypes were not suppressed by SGE1 in the multiple-copy state. Multiple copies of SGE1 increased expression of galactose-inducible genes in gal11 yeast, presumably at the level of transcription. When SGE1 was disrupted in wild-type yeast, the expression of galactose-inducible genes decreased to 50-60% of the wild-type level, presumably due to effect on transcription. Complete DNA sequence analysis revealed that SGE1 encodes a predicted protein of 543 amino acids. SGE1-specific mRNA of 1.8 kilonucleotides was detected by Northern analysis along the direction of the open reading frame. The gene mapped near RAD56, at the right end of chromosome 16.

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