F plasmids
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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].
