Mig1 is involved in mycelial formation and expression of the genes encoding extracellular enzymes in Saccharomycopsis fibuligera A11

Abstract

The MIG1 gene of Saccharomycopsis fibuligera A11 was cloned from its genomic DNA using the degenerated primers and inverse PCR. The MIG1 gene (1152 bp, accession number: HM450676) encoded a 384-amino acid protein very similar to Mig1s from other fungi. Besides their highly conserved zinc fingers, the Mig1 proteins displayed short conserved motifs of possible significance in glucose repression. The MIG1 gene in S. fibuligera A11 was disrupted by integrating the HPT (hygromycin B phosphotransferase) gene into ORF (Open Reading Frame) of the MIG1 gene. The disruptant A11-c obtained could grow in the media containing hygromycin and 2-deoxy- d-glucose, respectively. α-Amylase, glucoamylse, acid protease and β-glucosidase production by the disruptant and expression of their genes in the disruptant were greatly enhanced. This confirms that Mig1, the transcriptional repressor, indeed regulates expression of the genes and production of the extracellular enzymes in S. fibuligera A11. At the same time, it was found that cell budding was enhanced and mycelial formation was reduced in the disruptant.