Sequencing of the beta-isopropylmalate dehydrogenase gene (LEU2) from Acremonium chrysogenum and its application to heterologous gene expression

The nucleotide sequence of the Acremonium chrysogenum beta-isopropylmalate dehydrogenase gene (LEU2) was determined. The LEU2 gene encoded a polypeptide composed of 380 amino acid residues with a molecular weight of 40,637 Da, The predicted amino acid sequence had a high degree of similarity (47%) with that of the Saccharomyces cerevisiae LEU2 gene, A 1.4 kb transcript, which was repressed in the presence of leucine, was detected. A fused gene, LEU2-HPT consisting of the LEU2 promoter and the open reading frame of the bacterial hygromycin B phosphotransferase (HPT) gene was constructed and could be used as a dominant selectable marker in an A. chrysogenum transformation system. Moreover, the Escherichia coli B-galactosidase gene (lacZ) was expressed under the control of the LEU2 promoter in A. chrysogenum.