Objective: To develop an effective method for screening recombinant hairpin RNA expression plasmids using single restriction endonuclease analysis.
Methods: The double-strand DNA fragment containing a ClaI site (the flanking sequences of which were not complementary) was annealed and ligated into small hairpin RNA (shRNA) expression vector pSilencer-4.1 that did not contain ClaI site to construct the circular pSilencer-4.1-ClaI vector. With BamHI and HindIII, the pSilencer-4.1-ClaIwas digested and ligated with the DNA template of green fluorescence protein (GFP) shRNA that did not include a ClaI site. The plasmid DNA of the positive clones was extracted and digested with ClaI, and the inserted DNA sequence of the non-linearized plasmid was identified by sequence analysis.
Result and conclusion: DNA sequencing showed that pSilencer-4.1-ClaI was correctly constructed and the plasmids resistant to ClaI digestion were all recombinant vectors encoding GFP shRNA. The constructed pSilencer-4.1-ClaI can be used as a universal vector to construct the shRNA expression plasmid, and the incorporated ClaI sites may allow efficient screening of recombinant shRNA expression vectors.