Bacterial Artificial Chromosomes (BAC) consist in genetic material created in laboratory that contain a gene of interest from a given species cloned into a bacterial F-plasmid. At the end it will result in million copies of DNA.
The F-plasmids are very important since they promote the even distribution of plasmids after bacterial cell division, due
to the activity of the genes oriS, parA and
parB.
Thus, BAC has common gene components as:
- oriS and rep E-F, implicated on plasmid replication and posterior regulation of copy number;
- parA and parB, for partitioning F plasmid DNA to daughter cells during division and ensure stable maintenance of the BAC;
- lacZ, used for blue/white selection of recombinant bacterial colonies;
- ampicillin resistance gene, used as a selectable marker for transformants;
- gene inserted, part of the genome for cloning;
- T7 & Sp6, which are phage promoters implicated on the transcription of the inserted genes.
The Bacterial Artificial Chromosomes are useful for gene insertion with length until 300 kb. For human genomic
libraries, 32000 clones would be needed for a given gene to be represented (for
P=95%) or 50000 (for P=99%).
Cláudio Oliveira
Hélder Badim
Liliane Barroso
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