DNA cloning vectors containing regions of the P1 phage (q.v.) genome (q.v.) and capable of accepting large DNA inserts (i.e., up to 100 kilobases long). In this system, vector DNA and DNA fragments to be cloned are ligated and packaged in vitro into phage particles that can infect Escherichia coli. Once inside the bacterium, the packaged DNA is circularized and maintained as a plasmid (q.v.). A P1 plasmid replicon (q.v.) maintains the DNA at one copy per cell, and a P1 lytic replicon induces amplification of plasmid DNA under appropriate experimental conditions, allowing the isolation of large amounts of DNA for analysis. PACs are useful for cloning large genes, chromosome walking (q.v.), physical mapping, and shotgun sequencing (q.v.) of complex genomes. Compare with bacterial artificial chromosomes (BAC)s, yeast artificial chromosomes (YACs). See bacteriophage packaging, DNA vector, genomic library, kilobase, physical map, plasmid cloning vector.
Subjects: Genetics and Genomics.