Effects of codon optimization on expression in Escherichia coli of protein-coding DNA sequences from the protozoan Eimeria

The objective of this study was to compare the levels of recombinant protein from three Eimeria genes before and after optimization of codons for expression in Escherichia coli. Protein coding sequences from Eimeria maxima (EmaxSO7, EmaxIMP1) and Eimeria acervulina (EAH00033530) were cloned with or without prior codon optimization and expressed as polyHis fusion proteins. All three outcomes: higher, lower, or no change in the yield of amount of recombinant protein were observed suggesting that codon optimization alone for expression in E. coli does not inevitably lead to higher expression levels. Analysis of codon usage for each gene sequence revealed that, similar to other organisms, Eimeria intersperses rare and frequently used codons in protein-coding sequences. However, no relationship was observed between the predicted protein structure and the location of major and minor codons, suggesting that codon selection in this apicomplexan parasite is influenced by factors other than regional secondary protein structure.

Automated summary

The objective of this study was to compare the expression levels of recombinant proteins from three Eimeria genes in Escherichia coli before and after codon optimization. Codon optimization alone did not necessarily lead to higher expression levels, as the outcomes varied with some proteins showing higher, lower, or no change in yield. The codon usage analysis revealed that Eimeria, like other organisms, uses both rare and frequently used codons in its protein-coding sequences, but there was no correlation between codon usage and protein structure.