Comparative Study on the Effect of Signal Peptide Codons and Arginine Codons on the Expression of Human Interferon-α1 Gene inEscherichia coli

Abstract

Human interferon-alpha 1 (HuIFN-alpha 1) gene containing signal peptide codons is poorly expressed in bacteria, and this is explained by the presence of clusters of rare (AGG) arginine codons in its structure. In this study, we have constructed a series of modified HuIFN-alpha 1 genes to study the effect of both residual signal peptide codons and clusters of AGG codons on gene expression in Escherichia coli cells. Our results showed that substitution of preferential for rare arginine codons in two clusters did not affect the yield, whereas deletion of the signal peptide codons led to a 10-fold increase in the yield of recombinant protein. To understand the mechanism of interference of gene structure on the expression of the HuIFN-alpha 1 gene in vivo, both the level and stability of HuIFN-alpha 1 mRNA were measured. The amount of HuIFN mRNA increased almost five times on deletion of the signal peptide codons from HuIFN-alpha 1 gene constructs (containing AGG clusters or not). The stability of mRNA obtained from all gene constructs was shown to be the same (half-life of 60 +/- 5 secs), indicating that the signal peptide codons interfere with both the efficiency of transcription of the HuIFN-alpha 1 gene and translation of its mRNA.