Gene clusters, biosynthetic

The majority of industrial research describes classical approaches to yield improvement (49). However, there has been some work using genetically modified organisms. In the case of these recombinant organisms, the carotenoid biosynthetic gene cluster has been expressed in noncarotegenic species such as E. coli (50) and S. cerevisiae (51). 

Table 11.1 Predicted sizes and proposed functions of each protein product of the mitomycin C biosynthetic gene cluster.

There has been one report on the biosynthesis of FR900482 [114]. Radiolabeled D-glucosamine 33 and AHBA 38 were efficiently incorporated into 6, and D-[l-13C]-glucosamine was incorporated in the expected orientation (Figure 11.10). The biosynthetic gene cluster for FR900482 has been isolated from Streptomyces sandaensis and indicates a strong biosynthetic relationship with mitomycin C (Y. Mao, D. H. Sherman, unpublished results). 

Jin, M., Fischbach, M.A. and Clardy, J. (2006) A biosynthetic gene cluster for the acetyl-CoA carboxylase inhibitor andrimid. Journal of the American Chemical Society, 128, 10660-10661. 

Figure 11.6 The patE gene in the patellamide biosynthetic gene cluster encodes the peptide precursor (sequence in rectangle box) of patellamide C and ulithiacyclamide. Substitution of the precursor cassette for ulithiacyclamide with an artificial cassette (sequence in ellipse region) resulted in the biosynthesis of a new unnatural peptide, eptidemnamide...

Galm, U. and Shen, B. (2006) Expression of biosynthetic gene clusters in heterologous hosts for natural product production and combinatorial biosynthesis. Expert Opinion on Drug Discovery, 1, 409. 

Brikun, I.A., Reeves, A.R., Cernota, W.H. et al. (2004) The erythromycin biosynthetic gene cluster of Aeromicrobium erythreum. Journal of Industrial Microbiology Biotechnology, 31, 335. 

Liu, W., Nonaka, K., Nie, L. et al. (2005) The neocarzinostatin biosynthetic gene cluster from Streptomyces carzinostaticus ATCC 15944 involving two iterative type I polyketide synthases. Chemistry Biology, 12, 293. 

Van Lanen, S.G., Oh, T.J., Liu, W. et al. (2007) Characterization of the maduropeptin biosynthetic gene cluster from Actinomadura madurae ATCC 39144 supporting a unifying paradigm for enediyne biosynthesis. Journal of the American Chemical Society, 129, 13082. 

Miao, V., Brost, R., Chappie, J. et al. (2006) The lipopeptide antibiotic A54145 biosynthetic gene cluster from Streptomyces fradiae. Journal of Industrial Microbiology Biotechnology, 33, 129. 

Muller, C., Nolden, S., Gebhardt, P. et al. (2007) Sequencing and analysis of the biosynthetic gene cluster of the lipopeptide antibiotic friulimicin in Aclinoplanesfriuliensis. Antimicrobial Agents and Chemotherapy, 51, 1028. 

Particularly important to the pathways of modular synthases is the incorporation of novel precursors, including nonproteinogenic amino acids in NRP systems [17] and unique CoA thioesters in PK and fatty acid synthases [18]. These building blocks expand the primary metabolism and offer practically unlimited variability applied to natural products. Noteworthy within this context is the contiguous placement of biosynthetic genes for novel precursors within the biosynthetic gene cluster in prokaryotes. Such placement has allowed relatively facile elucidation of biosynthetic pathways and rapid discovery of novel enzyme mechanisms to create such unique building blocks. These new pathways offer a continued expansion of the enzymatic toolbox available for chemical catalysis. 

The activity of PK and NRPSs is often precluded and/or followed by actions upon the natural products by modifying enzymes. There exists a first level of diversity in which the monomers for respective synthases must be created. For instance, in the case of many NRPs, noncanonical amino acids must be biosynthesized by a series of enzymes found within the biosynthetic gene cluster in order for the peptides to be available for elongation by the NRPS. A second level of molecular diversity comes into play via post-synthase modification. Examples of these activities include macrocyclization, heterocyclization, aromatization, methylation, oxidation, reduction, halogenation, and glycosylation. Finally, a third level of diversity can occur in which molecules from disparate secondary metabolic pathways may interact, such as the modification of a natural product by an isoprenoid oligomer. Here, we will cover only a small subsection of... 

Leadlay, P.F., Staunton, J., Oliynyk, M. et al. (2001) Engineering of complex polyketide biosynthesis — insights from sequencing of the monensin biosynthetic gene cluster. Journal of Industrial Microbiology Biotechnology, 27 (6), 360-367. 

Ikeda, H., Nonomiya, T., Usami, M. et aL (1999) Organization of the biosynthetic gene cluster for the polyketide anthelmintic macrolide avermectin in Streptomyces avermitilis. Proceedings of the National Academy of Sciences of the United States of America, 96, 9509-9514. 

Becker, J.E., Moore, R.E. and Moore, B.S. (2004) Cloning, sequencing, and biochemical characterization of the nostocyclopeptide biosynthetic gene cluster molecular basis for imine macrocyclization. Gene, 325, 35 42. 

With the use of gene clusters of the natural products coronatine and kutznerides, the biosynthetic pathway of coronamic acid has also been elucidated by Walsh and coworkers. From the biosynthetic analyses, a nonheme Fe -dependent halogenase was identified as the chlorinating enzyme that converts L- //a-isoleucine to 7-chloroisoleucine. A second enzyme carries out a dehydrochlorination reaction to yield coronamic acid. The general biosynthetic pathway is shown below (Scheme 7). 

S. Boakes J. Bargallo Cortes M. J. Dawson, Lantibiotic Biosynthetic Gene Clusters from A. garbadinensis and A. liguriae. WO 2007/083112 A2, 2007. 

Proctor, R.H. et al.. Co-expression of 15 continuous genes delineates a fumonisin biosynthetic gene cluster in Gibberella monilifromis, Fungal Genet. Biol., 38, 237, 2003. 

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