The importance of arginine codons AGA and AGG for the expression in E. coli of triosephosphate isomerase from seven different species

- Triosephosphate isomerases from different species have different numbers of rare codons for E. coli.
- They only have rare codons for Arg, which distribute differently in the corresponding sequence.
- Protein expression in E. coli strain CP (DE3)-RIL increases with the number of rare codons for Arg.

Rare arginine codons AGA and AGG affect the heterologous expression of proteins in Eschericha coli. The tRNAs necessary for protein synthesis are scarce in E. coli strain BL21(DE3) pLysS and plentiful in strain BL21(DE3) CodonPlus −RIL. We evaluated in both bacterial strains the effect of these rare codons on the expression of triosephosphate isomerases from 7 different species, whose sequences had different dispositions of rare arginine codons. The ratio of expressed protein (CP/Bl21) correlated with the number of rare codons. Our study shows that the number, position and particularities of the combination of rare Arg codons in the natural non-optimized sequences of the triosephosphate isomerases influence the synthesis of heterologous proteins in E. coli and could have implications in the selection of better sequences for engineering enzymes for novel or manipulated metabolic pathways or for the expression levels of non enzymatic proteins..