Shuttle phasmid

Shuttle phasmids, sometimes called phagemids, are chimeric DNA vectors that replicate as plasmids in Escherichia coli as mycobacteriophages and in mycobacteria.^[1]

Shuttle phasmids, sometimes called phagemids,^[2] allow the insertion of foreign genetic material into the mycobacterial genome through homologous recombination (HR) or transposons.^[3]

Transformation efficiencies achieved through shuttle phasmids far exceed those resulting from electroporation.^[4]

In 1987, William Jacobs Jr. et al. utilized a shuttle phasmid for the first successful introduction of foreign DNA into mycobacteria. The employed shuttle phasmid—a term they coined—consisted of an E. coli bacteriophage lambda cosmid inserted into a non-essential region of mycobacteriophage TM4.^{[5] [4]}

Bardarov et al first created temperature-sensitive shuttle phasmids that replicate and form plaques at 30°C but are unable to do so at 37°C.^[4]

Bardarov et al also adapted shuttle phasmids to insert or knock out genes via homologous recombination, a process termed specialized transduction.^[4]

Shuttle phasmids enabled the isolation of mc2155, the fist plasmid-transformable Mycobacterium smegmatis strain.^[6]