A repressor activator protein1 homologue from an oleaginous strain of Candida tropicalis increases storage lipid production in Saccharomyces cerevisiae.

Abstract

The repressor activator protein1 (Rap1) has been studied over the years as a multifunctional regulator in Saccharomyces cerevisiae. However, its role in storage lipid accumulation has not been investigated. This report documents the identification and isolation of a putative transcription factor CtRap1 gene from an oleaginous strain of Candida tropicalis, and establishes the direct effect of its expression on the storage lipid accumulation in S. cerevisiae, usually a non-oleaginous yeast. In silico analysis revealed that the CtRap1 polypeptide binds relatively more strongly to the promoter of fatty acid synthase1 (FAS1) gene of S. cerevisiae than ScRap1. The expression level of CtRap1 transcript in vivo was found to correlate directly with the amount of lipid produced in oleaginous native host C. tropicalis. Heterologous expression of the CtRap1 gene resulted in ∼ 4-fold enhancement of storage lipid content (57.3%) in S. cerevisiae. We also showed that the functionally active CtRap1 upregulates the endogenous ScFAS1 and ScDGAT genes of S. cerevisiae, and this, in turn, might be responsible for the increased lipid production in the transformed yeast. Our findings pave the way for the possible utility of the CtRap1 gene in suitable microorganisms to increase their storage lipid content through transcription factor engineering.