Specific recombination in vitro promoted by the restriction endonuclease HgaI

We describe the use of the restriction endonuclease HgaI from Haemophilus gallinarum for the efficient construction in vitro of recombinant molecules. Using bacteriophage f 1 DNA, we show that only HgaI fragments that were originally adjacent on the genome are ligated, that upon ligation infectious molecules are reassembled with high efficiency, and that recombinant genomes can thus be easily constructed. The method relies upon the unique properties of HgaI and is applicable to any viral or plasmid DNA that contains several HgaI recognition sites.