Enhanced heterologous gene expression in diploid cells of methylotrophic yeast Hansenula (Ogataea) polymorpha

Abstract

The expression of bacterial gusA gene encoding for E. coli enzyme β-glucuronidase in haploid and diploid cells of methylotrophic yeast Hansenula (Ogataea) polymorpha was studied. Haploid strains were transformed with plasmid carrying gusA gene under the control of strong alcohol oxidase (AOX) promoter and several Gus+ transformants were isolated. They were crossed with wild type strains lacking Gus activity. The resulting diploids were sporulated and several meiotic segregants with increased Gus activity were isolated. Some of these segregants were crossed and the corresponding diploid strains were obtained. It was found that Gus activity of diploid strains was twice higher compared to haploids, whereas Gus activity of diploids was increased about six fold compared to those of haploids. Our results can be used as an approach for development of yeast strains with elevated expression of heterologous proteins.

Keywords

• Ogataea (Hansenula) polymorpha
• β-glucuronidase
• diploid strains