Construction and identification of nine single-point mutant recombinant plasmids of phenylalanine hydroxylase gene / 解放军医学杂志

ABSTRACT

Objective To perform PCR site-directed mutagenesis of nine novel PAH gene mutations (Y154H, R157I, Y206C, G247R, D282G, G346R, S349A, A389G, R400K) identified in northern Chinese and construct mutant recombinant plasmids of PAH gene. Methods 1) Every mutant recombinant plasmid was constructed according to the site of the mutation localized in functional domain of PAH gene and the related clinic phenotype of patients with the gene mutation. 2) Using the wild-type PAH expression vector as a templet, the mutant recombinant plasmids were directly amplified by PCR with Platinium Taq DNA polymerase and nine pairs of primers which were designed according to the human PAH cDNA sequence and the requirement for site-directed mutagenesis technology. 3) The positive strains were selected by Amp resistant test, PCR and restriction endonuclease analysis. The Mva Ⅰ, Mva Ⅰ, Hind Ⅲ, Rsa Ⅰ, Rsa Ⅰ sites exist in the sequences near the mutant sites of S349A, D282G, G247R, Y206C, Y154H, respectively, but not in the related sequence of wild-type PAH expression vector. Restriction endonuclease digestion could be directly used in identifying the mutant sites. However, the amplification created restriction site (ACRS) analysis was supplied in the followed identification of R157I, G346R, A389G, R400K. Finally the sequences of mutant recombinant plasmids of PAH gene were confirmed by DNA sequence analysis. Results Every sequence analysis showed that the mutant nucleic acids were introduced at the expected sites of PAH gene, suggesting that the mutant recombinant plasmids of PAH gene were constructed successfully. Conclusion PCR site-directed mutagenesis is accurate and highly efficient. The successfully mutagenized plasmids of PAH gene lay the foundation for the functional analysis of phenylalanine hydroxylase in mammalian cell system.