Eukaryotes genetic engineering

Kingsman, S.M. and Kingsman, AJ. (1988). Genetic Engineering An Introduction to Gene Analysis and Exploitation in Eukaryotes, Blackwell Scientific Publications, Oxford, UK, pp 522. 

Commensal bacteria, capable of colonizing mucosal surfaces, which are genetically engineered to express viral, bacterial, or eukaryotic antigens to produce an immune response... 

Ricin is a type II toxin. The A chain (ricin A) contains 267 amino acid residues, and the B chain (ricin B) 262 residues. Ricin A is exceptionally toxic, and it has been estimated that a single molecule is sufficient to kill an individual cell. This peptide can be prepared by genetic engineering using Escherichia coli. The potent action of this material on eukaryotic cells has been investigated in anticancer therapy. Ricin A has been coupled to monoclonal antibodies and successfully delivered specifically to the tumour cells. However, in vitro toxicity of ricin A-based immunotoxins is enhanced significantly if ricin B is also present. 

Kelly, R. F. and Winkler, M. E. (1990) Folding of eukaryotic proteins produced in Escherichia coli. Genetic Engineering 12(1), pp. 1-9. 

In plants and some other eukaryotes, pentoses are components of cell wall polysaccharides such as xylans and arabinogalactans. More interestingly, all green forms of life, i. e., those that perform photosynthesis, contain ribulose 1,5-bisphosphate carboxylase/oxygenase (often abbreviated as Rubisco) as the central enzyme involved in carbon dioxide fixation. Consequently, this enzyme has become of interest in numerous genetic engineering projects aimed at the improvement of photosynthesis in agriculturally important plants [4]. 

For some considerable time, it was thought that the genetic code was universal, especially because genetic-engineering experiments showed repeatedly that eukaryotic genes could be expressed in bacteria such as E. coli. More recently, however, it has been found that mitochondria have their own genetic code and protein-synthetic machinery. This has led to discussions about the evolutionary origin of mitochondria, a topic that cannot be pursued here. 

Over the past 30 years, a few researchers have reported the presence of xylose isomerase in a number of yeasts and fungi capable of rapid xylose metabohsm. Because of difficulties in using genetically engineered Saccharomyces, Freer et al. [38] re-examined Rhodosporidium toruloides to see if they could confirm an earlier report that this yeast produces xylose isomerase. They reasoned that the heterologous expression of an eukaryotic enzyme could fadfitate genetic engineering of xylose metabolism in S. cerevisiae. Unfortunately, they found that R. toruloides uses an oxidoreductase system fike other eukaryotes. Other approaches, however, have been more successful. 

In spite of the progress that has been made, several difficulties limit the use of cell-free enzymes for the synthesis of polysaccharides. The major problem is the complexity of many polysaccharide-synthesizing systems. Isolation, purification, and stabilization of the required enzymes is often difficult, as many enzymes lose activity when they are no longer membrane-associated. Enzyme isolation from eukaryotic sources is tedious, because of low cellular enzyme concentration. It is unlikely that cell-free enzymatic synthesis will provide better routes to most natural polysaccharides than do fermentation and isolation. The use of genetic engineering,... 

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