The MIG1 repressor from Kluyveromyces lactis: cloning, sequencing and functional analysis in Saccharomyces cerevisiae

Sequence comparisons between Saccharomyces cerevisiae ScMig1 and Aspergillus nidulans CREA proteins allowed us to design two sets of degenerate primers from the conserved zinc finger loops. PCR amplification on Kluyveromyces marxianus and K. lactis genomic DNA yielded single products with sequences closely related to each other and to the corresponding regions of ScMig1 and CREA. The KIMIG1 gene of K. lactis was cloned from a genomic library using the K. marxianus PCR fragment as probe. KIMIG1 encodes a 474-amino acid protein 55% similar to ScMig1. Besides their highly conserved zinc fingers, the two proteins display short conserved motifs of possible significance in glucose repression. Heterologous complementation of a mig1 mutant of S. cerevisiae by the K. lactis gene demonstrates that the function of the Mig1 protein is conserved in these two distantly related yeasts.