Isolation and Characterization of a Salt Inducible Promoter from Chlorella vulgaris PKVL7422

Abstract

Chlorella is a eukaryotic organism that can be used as an industrial host to produce recombinant proteins. In this study, a salt-inducible promoter (SIP) was isolated from the freshwater species Chlorella vulgaris PKVL7422 from the screening of genes that were upregulated after salt treatment. Several cis -acting elements, including stress response elements, were identified in the isolated SIP. Moreover, the Gaussia luciferase gene was cloned after the SIP and transformed into C. vulgaris to test the inducibility of this promoter. Reexamination of transcriptome of C. vulgaris revealed that genes involved in the synthesis of methyl jasmonic acid (MeJA), gibberellin (GA), and abscisic acid (ABA) were upregulated when C. vulgaris was treated with salt. Furthermore, the expression level of recombinant luciferase increased when the transformed C. vulgaris was treated with salt and MeJA, GA, and ABA. This study represents the first report of the C. vulgaris SIP and highlights how transformed microalgae could be used for robust expression of recombinant proteins.

High-Level Expression of Recombinant VHSV Glycoprotein Using Transformed C. vulgaris and Verification of Vaccine Efficacy

“…To increase the expression level of recombinant protein, C. vulgaris expressing the VHSV glycoprotein was developed using the SIP developed in a previous study [50]. Although the yield of recombinant protein can be increased with NaCl treatment, the growth of transformed C. vulgaris was also affected by NaCl concentration because this is a freshwater Chlorella strain.…”