Asparaginase II-GFP fusion as a tool for studying the secretion of the enzyme under nitrogen starvation

Abstract

Production of asparaginase II of Saccharomyces cerevisiae is regulated by nitrogen and can be used as a model system for studying other secreted proteins in yeast. Green fluorescent protein (GFP) from Aequorea victoria was fused to the carboxy-terminus of the enzyme by genomic integration to the locus ASP3 of S. cerevisiae. We determined asparaginase II activity, mRNAASP3, mRNAASP3-GFP and GFP fluorescence. Nitrogen starvation in cells carrying the chimera ASP3-GFP caused an increase in fluorescence and in the expression of ASP3. We have shown that cells producing the chimera Asp3-GFPp displayed the same response to nitrogen starvation as control cells. We demonstrated that Asp3-GFPp can be used for studying asparaginase II secretion under nitrogen starvation in vivo.