F plasmids

in progress!

F plasmid derived replication origins

There are at least 3 kinds of replication origins that are derived from the F factor of Escherichia coli.

mini-F

• includes oriS and repE
• ~1.6 kb
• used in pSCANS (genbank vector info cookbook) or pSB2K3-P1010 series plasmids
• at copy number 4-6?

F plasmid derived origin used in most BACs

• includes oriS, repE and the par genes
• ~4.6 kb
• used in pBeloBAC11 and other BACs
• at copy number 4-6

"complete" F origin

• includes repC, oriV, ccd operon, repD, oriS, repE and the par genes
• ~9kb
• used by Kris Prather in her F plasmids that she built when in Jay Keasling's lab [1]
• at copy number 1-2

Nomenclature

• Episome: A circular piece of DNA that can replicate independently of the bacterial chromosome or integrate and replicate as part of the chromosome.
• F factor: An episome in bacterial cells that confers the ability to act as a genetic donor during conjugation.
• F+ cell: A bacterial cell possessing the fertility factor. Acts as a donor in conjugation.
• F- cell: A bacterial cell that does not contain a fertility factor. Acts as a recipient in conjugation.
• F' cell: A bacterial cell in which an integrated fertility factor spontaneously excises itself, taking part of the chromosome with it. The resulting episome therefore contains chromosomal material.
• Hfr cell: A strain of bacteria exhibiting a high frequency of recombination, due to a chromosomally-integrated fertility factor. This strain is able to transfer all or part of the chromosome to recipient strains.

From [2].

Mating types

• F+ mating with F- produces 2 F+
• Hfr mating with F- produces Hfr and F-
• F' mating with F- produces F' and F' merozygote

From [2].

References

1. Jones KL and Keasling JD. Construction and characterization of F plasmid-based expression vectors. Biotechnol Bioeng. 1998 Sep 20;59(6):659-65.

2. Biol301 at Eastern Michigan University