Gene recombination

DNA ligase is not only important in DNA replication it is also used to seal deoxyri-bonucleotide segments in the crossover events during gene recombination. The enzyme also functions to close breaks in segments of DNA undergoing repair and is required to join theends of mitochondrial DNA to form their characteristic circular structure. 

Keywords. Polyhydroxyalkanoates, PHA biosynthesis genes, Recombinant bacteria, Fermentation... 

A Ca +-binding protein isolated from jellyfish Aequorea sp.) that is frequently used as a chemiluminescent calcium indicator.Aequorin contains a hydrophobic prosthetic group, coelenterazine. Investigators have been able to express the transfected gene recombinantly in a number of cells, and upon addition of the cofactor, one can measure intracellular calcium concentration. See Fura-2... 

The detailed characterization of hydroxynitrile lyases from Sorghum hicolor (E.C. 4.1.2.11) and Linum usitassimum (E.C. 4.1.2.37) has been hampered for a long time due to the lack of a recombinant expression system. Therefore our studies were focused on cloning of the coding genes, recombinant expression, and characterization of these enzymes. 

Although with the advent of gene recombination technology the knowledge of enzymes is gaining rapidly, their principal characteristics have been established for decades. These include sensitivity to the environment... 

Kelley, D.E., Wiedemann, L.M., Pittet, A.-C., Strauss, S., Nelson, K.J., Davis, J., Van Ness, B., Perry, R.P. (1985). Nonproductive kappa immunoglobulin genes recombinational abnormalities and other lesions affecting transcription, RNA processing, turnover, and translation. Mol. Cell. Biol. 5,1660-1675. 

Max, E.E., Seidman, J.G., Miller, H., Leder, P. (1980). Variation in the crossover point of kappa immunoglobulin gene recombination evidence from a cryptic gene. Cell 21,793-799. 

Seising, E., Voss, J., Storb, U. (1984). Immunoglobulin gene remnant DNA—implications for antibody gene recombination. Nucleic Acids Res. 12,4229-4246. 

Laskey, R.A., Honda, B.M., Mills, A.D., Finch, J.T. (1978). Nucleosomes are assembled by an acidic protein which binds histones and transfers them to DNA. Nature (London) 275,416-420. Lederberg, J. Tatum, E.L. (1946). Gene recombination in E. coli. Nature (London) 158, 558. Macfarlane, R.G. (1964). An enzyme cascade in the blood clotting mechanism and its function as a biochemical amplifier. Nature (London) 202,498-499. 

Recombination is a powerful force in natural evolution it serves to propagate positive traits and eliminate negative traits in progeny. Stemmer has described a method for random gene recombination in vitro, which he calls DNA shuffling or sexual PCR [7.8], Initially, the DNA from a collection of enzyme variants to be shuffled is amplified by PCR. The resulting DNA is... 

Gene recombination can be implemented both in vivo and in vitro. However, the latter is used much more often because of its simplicity, higher recombination efficiency, and flexibility. Therefore, only in vitro methods will be discussed here. Note that all the available in vitro gene recombination methods fall into two main categories homology-dependent and homology-independent. 

Figure 3 Comparison of various gene recombination methods, including (a) DNA shuffling, (b) StEP, (c) ITCHY, and (d) SHIPREC.

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