Chimeric DNA molecule

The first biologically functional chimeric DNA molecules constructed in vitro were assembled from parts of different plasmids in 1973 by Stanley Cohen, Annie Chang, Herbert Boyer, and Robert Helling. These plasmids were used to transform recipient E. coli cells transformation means the uptake and repli-... 

Chimeric DNA molecules are introduced into cells to make transfected cells or into the fertilized oocyte to make transgenic animals. 

Fig. 24.3 The construction of a chimeric (or recombinant) DNA molecule hy joining together two DNA fragments produced by cleavage of different parental DNA molecules with the same restriction endonuclease.

Restriction fragments of DNA can be used to identify variations in base sequence in a gene. However, they also can be used to synthesize a recombinant DNA (also called chimeric DNA), which is composed of molecules of DNA from different... 

DNA molecules containing covalently linked segments derived from two or more DNA sources are called recombinant DNA. (Another name for recombinant DNA is chimeric DNA, named after the chimera, a monster in Greek mythology that had the head of a lion, the body of a goat, and the tail of a serpent.) The production of recombinant DNA was made possible by the isolation of restriction endonucleases. 

A plasmid, which is a circular DNA molecule separate from the chromosomal DNA, is obtained from bacterial cells such as Escherischia coli and treated with a restriction enzyme to snip the DNA at a specific site (Figure 26.15). The human DNA sequence that codes for the synthesis of insulin is then inserted into the plasmid to give a recombinant DNA molecule. The new DNA is the result of the recombination of DNA from the plasmid plus the sequence that codes for human insulin. The new plasmid is termed a chimeric plasmid because it contains DNA from two sources, bacterial and human. The plasmid is taken up by growing bacterial cells through a process called transformation. The chimeric plasma serves as a cloning vector because it serves as a vehicle to carry the recombinant DNA into E. coli. Transcription and translation of the insulin DNA then occur to produce human insulin. When the cells divide, the plasmids are divided between the daughter cells and they continue to produce clones. Insulin produced by recombinant DNA technology is commercially sold as Humulin. 

RECOMBINANT DNA TECHNOLOGY INVOLVES ISOLATION MANIPULATION OF DNA TO MAKE CHIMERIC MOLECULES... 

Isolation and manipulation of DNA, including end-to-end joining of sequences from very different sources to make chimeric molecules (eg, molecules containing both human and bacterial DNA sequences in a sequence-independent fashion), is the essence of recombinant DNA research. This involves several unique techniques and reagents. 

Manipulation of the DNA to change its structure, so-called genetic engineering, is a key element in cloning (eg, the construction of chimeric molecules) and can... 

Chimeric molecule A molecule (eg, DNA, RNA, protein) containing sequences derived from two different species. 

The advent of recombinant DNA technology led to the development of antibodies and fragments that are tailored for optimal behaviour in vivo [7,8]. Humanized and chimeric antibodies can be constructed to circumvent the human anti-mouse antibody response elicited by mouse antibody treatment of patients, which severely hampers the application of these powerful molecules. The treatment of rheumatoid arthritis patients with doses of as high as 10 mg kg cA2 chimeric antibody specific for TNFa [9], emphasizes that at present the production and purification methods for these proteins have been optimized to such extent that clinical studies can be considerably intensified. 

Chemical inducers of dimerization (CID) are bivalent small molecules that bind t vo proteins simultaneously. The purpose of these molecules is to bring the proteins together to induce signal transduction [27]. For brevity, we will limit our discussion to CIDs that directly control transcription. The basic architecture of these systems consists of two chimeric proteins. The first contains a DNA-binding domain (DBD) fused to a ligand-binding domain (LBD) and the second chimera contains an LBD and an activation domain (AD). The small molecule that binds both of these proteins simultaneously induces proximity of the two proteins, resulting in transcription activation (Fig. 8.11). 

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