Construction of the expression plasmid pPICZ α A-EntA. A, The nucleotide sequence of EntA and its corresponding amino acid sequence. The upper line indicates the wild-type EntA gene sequence. The middle line is the codon-optimized EntA gene sequence. Optimized codons are underlined with boldface type. The lower line represents the amino acid sequence of EntA. The termination codon is marked by an asterisk. B, Map of the recombinant plasmid pPICZαA-EntA. C, Electrophoretic analysis of the recombinant vector containing the EntA gene. Lane 1, DNA marker; lane 2, pPICZαA-EntA digested by XhoI and XbaI.