A method is described for the direct cloning of DNA fragments amplifie
d by the polymerase chain reaction (PCR). An oligodeoxyribonucleotide,
bearing two engineered XcmI sites placed in tandem, was used to gener
ate cloning vectors bearing single 3' deoxythymidine (dT) overhangs at
their ends. These 3' dT overhangs are compatible with the 3' deoxyade
nosine overhangs found on most Tag polymerase-amplified PCR products.
Consequently, Taq polymerase-amplified PCR products can be ligated dir
ectly into these modified restriction sites.