Candida albicans UBI3 and UBI4 promoter regions confer differential regulation of invertase production to Saccharomyces cerevisiae cells in response to stress

Abstract.

Candida albicans ubiquitin genes UBI3 and UBI4 encode a ubiquitin-hybrid protein involved in ribosome biogenesis and polyubiquitin, respectively. In this work we show that UBI3 and UBI4 promoter regions confer differential expression consistent with the function of their encoded gene products. Hybrid genes were constructed containing the SUC2 coding region under the control of UBI3 or UBI4 promoters in the yeast vector pLC7. Invertase production in Saccharomyces cerevisiae transformants was differentially regulated: the UBI4 promoter was induced by stress conditions (thermal upshift and/or starvation) whereas the UBI3 promoter conferred constitutive invertase production in growing yeast cells. These results indicate that the UBI4 promoter is regulated by stress-response signaling pathways, whereas the UBI3 promoter is controlled according to the requirement for protein synthesis to support cell growth.