Copy-control pBAC/oriV vectors for genomic cloning.

The use of the improved BAC system for cloning genomic DNA and library constructions is described. This system retains all the advantages of the original BACs but, in addition, permits, on command, amplification of the BAC plasmids and cloned DNA. This system consists of (1) plasmid pBAC/oriV containing an additional replication origin, oriV, and (2) a host carrying the up-mutants of the trfA replicator gene expressed from the l-arabinose-inducible Para promoter. The pBAC/oriV clones are always maintained in the single-copy state, but if more DNA is required, they could be amplified up to 100-fold, depending on the size of the cloned insert.