Cloning and nucleotide sequencing of cholera toxin B subunit gene.

Cholera toxin B subunit(CTB) gene was amplified from plasmid pUCT1 by ploymerase chain reaction (PCR) and the site directed mutagenesis was used to mutate the stop codon,TAA, of CTB gene, to GAA.The PCR product was digested with restriction endonucleases, BamHⅠ and EcoRⅠ, and inserted into the vector pET 28b(+). By the analysis of restriction endonucleases and PCR, 309 bp CTB gene had been cloned and the recombinant plasmid pECTB was constructed. The result of nucleotide sequencing showed that cloned CTB gene had positive reading frame in the plasmid pECTB.