User:Yuqingli1015/P1-Derived Artificial Chromosome

Introduction
wiki stub article: P1-derived artificial chromosome

addition to 1st paragraph: P1-deriverd artificial chromosome, or PAC, is one of the efficient cloning vector that is used in Escherichia coli......

History of PAC
The bacteriophage P1 was first isolated by Dr. Giuseppe Bertani. In his study, he noticed that the lysogen was producing an abnormal non-continuous phages, and later he found out phage P1 was produced from lysogen Lisbonne strain, along with P2 and P3. P1 has the ability to copy one bacteria host genome and integrate that DNA information into another bacteria host, also known as generalized Transduction (genetics). Later on, ........... P1 vector system was developed so that it is able to carry relatively large DNA fragments in plasmid (95-100kb).

Construction
PAC has 2 loxP sites, which are useful for phage recombinase and the product from its cre gene recognition during Cre-Lox recombination. This process will circularize the DNA strand, which can be used for transforming into Escherichia coli. The transformation is usually done by Electroporation, which is a method to apply electric field, which allows plasmids entering the cells. If a high expression level is desired, P1 lytic replicon can be used in constructs.

Comparison with Other Artificial Chromosomes
PAC is one of the artificial chromosome vectors. Some other artificial chromosomes are: Bacterial artificial chromosome, Yeast artificial chromosome, Human artificial chromosome, etc. Compare to other artificial chromosomes, it can carry a relatively big DNA fragments, however it is less than Yeast artificial chromosome.

Application
PAC is commonly used as a large capacity vector which allows propagation of large DNA inserts in Escherichia coli. This feature has been commonly used for:


 * building genome libraries for human, mouse, etc
 * libraries served as the template for gene sequencing
 * genome analysis of more complex organisms (plants, animals etc.)
 * facilitate gene expression

Since PAC was derived from phage, it is also useful for phage therapy and antibiotic studies.