A highly efficient cell penetrating peptide pVEC-mediated protein delivery system into microalgae

Interest in microalgae has significantly increased due to its potential as a promising bioresource in various fields. However, a technique for intracellular delivery of proteins into microalgae has not established yet, although it is potentially valuable for advanced algal research. Here, we propose a cell penetrating peptide pVEC-mediated protein delivery tool for microalgae. We discovered that the peptide pVEC from vascular endothelial cadherin was more effective in transporting exogenous proteins into algal cells than other peptides including R9, Transportan, TAT and Penetratin. pVEC-mediated tool was shown to deliver proteins of various sizes from 6 kDa to 150 kDa into wild-type Chlamydomonas reinhardtii and to also work in other algal species such as Nannochloropsis salina and Chlorella vulgaris when delivering a 66 kDa protein. In addition, we show that our proposed pVEC-mediated protein delivery system is based on both the endocytic and non-endocytic pathways simultaneously through a mechanism study using inhibitors such as low temperature, N-ethylmaleimide, 5-(N-ethyl-N-isopropyl) amiloride, chlorpromazine, sodium azide, and methyl-beta-cyclodextrin. The results show that the proposed simple and efficient protein delivery tool could contribute to advanced algal research for a wide array of applications for microalgae in various industries.