Molecular and functional analysis of a MIG1 homologue from the yeast Schwanniomyces occidentalis

A putative glucose repressor MIG1-homologue (SoMIG1) was isolated from the amylolytic yeast Schwanniomyces occidentalis. Degenerate primers were designed from the conserved zinc finger regions of Mig1 and CreA proteins from different organisms. PCR using these primers and S. occidentalis genomic DNA as template yielded a single 128 bp product. This fragment was used as a DNA probe to screen a S. occidentalis genomic library. Analysis of the positive clones led to the isolation by PCR of a DNA fragment, which contained an open reading frame (ORF) that would encode a 458 amino acid polypeptide. The DNA binding and effector domains of this putative protein showed an identity of 71% and 15%, respectively, to those of the Mig1 protein from Saccharomyces cerevisiae. The SoMIG1 gene complemented a mig1 mutant of this yeast, which suggests that in S. occidentalis SoMIG1 is a glucose repressor. The Accession No. is AJ417892.