Protein expression of preferred human codon-optimized Gaussia luciferase genes with an artificial open-reading frame in mammalian and bacterial cells

•Secreted Gaussia luciferase (GLuc) is a potent candidate for the video-rate imaging.•Complete preferred human codon-optimized EpGLuc and KpGLuc were prepared.•EpGLuc and KpGLuc have an artificial open-reading frame (ORF).•An artificial ORF did not affect the gene expression in mammalian cells.

The protein expressions of three preferred human codon-optimized Gaussia luciferase genes (pGLuc, EpGLuc, and KpGLuc) were characterized in mammalian and bacterial cells by comparing them with those of wild-type Gaussia luciferase gene (wGLuc) and human codon-optimized Gaussia luciferase gene (hGLuc). Two synthetic genes of EpGLuc and KpGLuc containing the complete preferred human codons have an artificial open-reading frame; however, they had the similar protein expression levels to those of pGLuc and hGLuc in mammalian cells. In bacterial cells, the protein expressions of pGLuc, EpGLuc, and KpGLuc with approximately 65% GC content were the same and showed approximately 60% activities of wGLuc and hGLuc. The artificial open-reading frame in EpGLuc and KpGLuc did not affect the protein expression in mammalian and bacterial cells.