The silent point mutations at the cleavage site of 2A/2B have no effect on the self-cleavage activity of 2A of foot-and-mouth disease virus

The 2A region of the foot-and-mouth disease virus (FMDV) polyprotein is 18 amino acids in length, and 2A self-cleavage site (2A/2B) contains a conserved amino acid motif G2A/P2B. To investigate the synonymous codon usage for Glycine at the 2A/2B cleavage site of FMDV, 66 2A/2B1 nucleotide sequences were aligned and found that the synonymous codon usage of G2A is conserved and GGG was the most frequently used. To examine the role of synonymous codons for G2A in self-cleavage efficiency of 2A/2B, recombinant constructs which contains the chloramphenicol acetyltransferase protein (CAT) and enhanced green fluorescent protein (EGFP) linked by the FMDV 2A sequence with four synonymous codons for G2A were produced. The activities of all the F2As based plasmids were determined in CHO cells. The results showed that the synonymous codon usage patterns for G2A at the cleavage site (2A/2B) have no effect on the cleavage efficiency. This suggests that the synonymous codon usage of 2A peptide has no effect on the cleavage efficiency of FMDV 2A element.