Engineered biosynthesis

Much of protein engineering concerns attempts to explore the relationship between protein stmcture and function. Proteins are polymers of amino acids (qv), which have general stmcture +H3N—CHR—COO , where R, the amino acid side chain, determines the unique identity and hence the stmcture and reactivity of the amino acid (Fig. 1, Table 1). Formation of a polypeptide or protein from the constituent amino acids involves the condensation of the amino-nitrogen of one residue to the carboxylate-carbon of another residue to form an amide, also called peptide, bond and water. The linear order in which amino acids are linked in the protein is called the primary stmcture of the protein or, more commonly, the amino acid sequence. Only 20 amino acid stmctures are used commonly in the cellular biosynthesis of proteins (qv). 

Nucleic acids are the molecules of the genetic apparatus. They direct protein biosynthesis in the body and are the raw materials of genetic technology (see Genetic engineering). Most often polynucleotides are synthesized microbiologicaHy, or at least enzymatically, but chemical synthesis is possible. 

Biosynthesis of carotenoids with genetically engineered hosts . Patent PCT/US91/ 01458. 

YE X, AL-BABILI s, KLOTZ A, ZHANG J, LUCCA p, BEYER p and POTRYKUS I (2000) Engineering provitamin A ( 3-carotene) biosynthesis pathway into (carotenoid-free) rice endosperm . Science, 287, 303-5. 

We have chosen carotenoid biosynthesis as the example system for demonstrating the prospects of biotechnology of food colorants for several reasons. Carotenoid biosynthesis is the second most understood system. Multiple examples of valuable food colorant engineering in fungi, bacteria, and plants have been reported. Finally, carotenogenesis in cereal crops such as maize and rice is the primary focus of our research efforts. Hopefully, we provide the food technologist with a template with which to examine other industrially important pigment systems. 

Careful empirical selection of the expression platform for carotenogenesis has included selection of the best strains for stability and degree of accumulation and the selection of compatible drug-resistance combinations and low copy number polycistronic plasmids to enhance product accumulation by decrease of metabolic burden." 5 Matthews and Wurtzel discussed culture and induction conditions - that have been explored in most studies. Most efforts to engineer carotenoid biosynthesis in E. coli focused on the genes and enzymes of the pathway and had a modest effect on improved accumulation. For example, substitution and over-expression of a GGPPS that uses IPP directly (discussed in... 

Rohlin, L., Oh, M.K., and Liao, J.C., Microbial pathway engineering for industrial processes evolution, combinatorial biosynthesis and rational design, Curr. Opin. Microbiol. 4, 330, 2001. 

Introduces novel approaches to the biosynthesis of colorants by microalgae, microorganisms, and genetic engineering... 

Watts, K. T., R C. Lee et al. (2006). Biosynthesis of plant-specific stilbene polyketides in metabolically engineered Escherichia coli. BMC Biotechnol. 6 22. 

Chapters 11-13 are devoted to combinatorial biosynthesis, metabolic engineering, and autonomous enzymes for the synthesis and development of complex medicinal molecules. 

Figure 11.3 Principle of combinatorial biosynthesis. Genetic engineering and recombination of the biosynthetic pathways are two major strategies in combinatorial biosynthesis to expand structural diversity...

Figure 11.4 6-DEBS 1, 2 and 3 that are modularly organized PKSs direct the biosynthesis of erythromycin A (a), and genetic engineering on genes encoding DEBSs gave rise to various 6-DEB analogs (b)...

Shen, B., Liu, W. and Nonaka, K. (2003) Enediyne natural products biosynthesis and prospect towards engineering novel antitumor agents. Current Medicinal Chemistry, 10, 2317. 

Strohl, W.R. (2001) Biochemical engineering of natural product biosynthesis pathways. Metabolic Engineering, 3, 4. 

Kato, Y., Bai, L., Xue, Q. et al. (2002) Functional expression of genes involved in the biosynthesis of the novel polyketide chain extension unit, methoxymalonyl-acyl carrier protein, and engineered biosynthesis of 2-desmethyl-2-methoxy-6-deoxyerythronolide B. Journal of the American Chemical Society, 124, 5268. 

Kao, C.M., Luo, G.L., Katz, L. et al. (1995) Engineered biosynthesis of a triketide lactone from an incomplete modular polyketide synthase. Journal of the American Chemical Society, 117, 9105. 

Hojati, Z., Milne, C., Harvey B. et al. (2002) Structure, biosynthetic origin, and engineered biosynthesis of calcium-dependent antibiotics from Streptomyces coelicolor. Chemistry Biology, 9, 1175. 

Figure 12.1 The biosynthesis of 6dEB catalyzed by DEBS [58]. (From B.A. Pfeifer, S.J. Admiraal, H. Gramajo et al. Biosynthesis of complex polyketides in a metabolically engineered strain of E. coli. Science 291 1790-1792. Washington, DC AAAS. 2001 AAAS. Reprinted with permission from AAAS.)...

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