pUC19 Vector

pUC19 is a plasmid cloning vector first discovered by Joachim Messing and his team. It is a widely used vector for recombination, or for introducing foreign DNA into cells. The word “pUC” is derived from “p” denoting the word plasmid and the abbreviation for the University Of California, where the early work on this plasmid was conducted. Its colonies can be easily differentiated from colonies of other non-recombinant-based colonies based on their colour.

Also read- Plasmid Vectors For Gene Cloning – My Biology Dictionary

Structure of pUC19 Vector

pUC19 is similar to plasmid pBR322 in structure the only difference between the two is the single mutation and the lack of the rop gene which is responsible for its high copying nature. It has a double-stranded circular DNA, contains 2686 base pairs and has a weight of 1.75 x 10^6 Da.

pUC19 full form

p= plasmid

UC= University of California

19= numerical designation

The ampicillin resistance gene and the pMB1 replication origin from pBR322 have been used in its construction.
Different restriction enzyme sites are present in the plasmids. The more restriction sites there are, the more desired cloning fragments can be produced. The E. Coli lac operon and the 5′-terminal region of the lacZ gene, which codes for the N-terminal region of B-galactosidase, are both present in pUC19. The pUC19 vector has numerous restriction sites, including EcoR1, HindIII, BamH1, and numerous others.

Blue-White Screening Method for pUC19 Vector

The blue-white screening method is an efficient and rapid technique for the identification of recombinant bacteria. The technique relies on the activity of B-galactosidase which occurs in E.coli, that cleaves lactose into glucose and galactose.

Using this process, X-gal, a synthetic material, is hydrolyzed by B-galactosidase, resulting in the formation of a blue pigment. It produces galactose and 5-bromo-4-chloro-3-hydroxy indole as a result of X-gal hydrolysis. The latter dimerizes and oxidises to yield a blue material in the media.

As a result, on the agar media, cells expressing B-galactosidase activity produce blue colonies, while those lacking it form white colonies. Because they do not have B-galactosidase, the recombinant cells with the newly inserted DNA appear white.

Application of pUC19 Vector

The application of high copying vectors like pUC19 is increasing occasionally. The major role they play is in the field of molecular biology and genetic engineering due to their simplicity and cost-effectiveness. Some of their applications are as follows:

1. Cloning vectors are used in the transfer of foreign desirable DNA fragments into the host cell for various purposes.
2. They are used for the engineering of the E. coli bacteria for insulin production.
3. Cloning Vector can also be used to study various proteins’ structure and function.
4. They can be used to identify mutations in regions of the DNA and also gene defects as well.

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Team MBD