Abstract:
A method of identifying a DNA sequence containing a human origin of replication (hORI) is disclosed. The method includes the steps of (A) providing fragments of human genomic DNA suitable for cloning into a bacterial plasmid, (B) ligating the fragments into a bacterial plasmid comprising (i) a bacterial origin of replication, (ii) a bacterial selection marker, and (iii) a mammalian selection marker, (C) transforming bacterial host cells with the plasmid, (D) selecting transformed bacterial host cells using the bacterial selection marker, (E) isolating plasmid DNA from the transformed bacterial host cells, (F) transfecting human cells with the isolated plasmid DNA, (G) selecting transfected human cells using the mammalian selection marker, (H) isolating extrachromosomal DNA from selected human cells, (I) digesting a suspension of the extrachromosomal DNA with a restriction endonuclease capable of cleaving methylated, but not unmethylated DNA, and (J) purifying undigested extrachromosomal DNA from the suspension.