In addition to our work on artemisinin, the Keasling laboratory is determining the metabolic pathway responsible for synthesis of prostratin, a 20-carbon phorbol ester with anti-viral properties. This molecule, derived from the bark of the mamala tree, was first discovered by Samoan healers and used to treat hepatitis. Recently, this molecule has been shown to have anti-HIV properties. By determining the metabolic pathway responsible for its synthesis in the mamala tree and engineering microorganisms to produce it, we will have developed an environmentally friendly production system for the drug if it is approved.
Similarly, we are working on determining the missing steps in the Taxol pathway, a taxane diterpenoid used as an anti-cancer drug and produced by all species of the genus Taxus, the yew trees. Current methods of production still rely on a plant source, resulting in low and unstable yield, high production costs, and unwanted byproducts. Determining the metabolic pathway for its production should similarly lead to an engineered microbe to be used for production.
While many natural products have become important pharmaceuticals, most natural products are not ideal for treating human disease. To broaden the product range of metabolic pathways and develop alternatives to natural products that might be more suitable for treating human disease, we are examining and changing the substrate range of cytochrome P450 hydoxylases to oxygenate a broader range of terpenes than they would normally oxidize and to do so in different positions on the molecule than they would naturally oxidize. The resulting oxidized terpenes might be precursors for production of pharmaceuticals or other products.
- V. J. J. Martin, Y. Yoshikuni, and J. D. Keasling. 2001. “The in vivo synthesis of plant sesquiterpenes in Escherichia coli.” Biotechnol. Bioeng. 75:497-503.
- V. J. J. Martin, C. D. Smolke, and J. D. Keasling. 2002. “Redesigning cells for production of complex organic molecules.” ASM News 68:336-343.
- A. Magyarosy, J. Z. Ho, H. Rapoport, S. Dawson, J. Hancock, and J. D. Keasling. 2002. “Chlorxanthomycin, a fluorescent, chlorinated, pentacyclic pyrene from a Bacillus sp.” Appl. Environ. Microbiol. 68:4095-4101.
- C. Khosla and J. D. Keasling. 2003. “Metabolic engineering for drug discovery and development.” Nature Rev. Drug Disc. 2:1019-1025.
- Y. Yoshikuni, T. E. Ferrin, and J. D. Keasling. 2006. “Designed divergent evolution of enzyme function.” Nature 440:1078-1082.
- B. F. Pfleger, D. J. Pitera, C. D. Smolke, and J. D. Keasling. 2006. “Combinatorial engineering of intergenic regions in operons tunes expression of multiple genes.” Nat. Biotechnol. 24:1027-1032.
- M. C. Y. Chang and J. D. Keasling. 2006. “Production of isoprenoid pharmaceuticals by engineered microbes.” Nat. Chem. Biol. 2:674-681.
- S. T. Withers and J. D. Keasling. 2007. “Biosynthesis and engineering of isoprenoid small molecules.” Appl. Microbiol. Biotechnol. 73:980-990.
- D. J. Pitera, C. J. Paddon, J. D. Newman, and J. D. Keasling. 2007. “Balancing a heterologous mevalonate pathway for improved isoprenoid production in Escherichia coli.” Metab. Eng. 9:193-207.
- M. C. Y. Chang, R. A. Eachus, W. Trieu, D.-K. Ro, and J. D. Keasling. 2007. “Engineering Escherichia coli for production of functionalized terpenoids using plant P450s.” Nature Chem. Biol. 3:274-277.
- L. Kizer, D. J. Pitera, B. Pfleger, and J. D. Keasling. 2008. “Functional genomics for pathway optimization: application to isoprenoid production.” Appl. Environ. Microbiol. 74:3229-3241.
- J. Kirby and J. D. Keasling. 2008. “Metabolic engineering of microorganisms for isoprenoid production.” Nat. Prod. Rep. 25:656-661.
- J. D. Keasling. 2008. “From yeast to alkaloids” Nat. Chem. Biol. 4:524-525.
- W. Shui, L. Sheu, J. Liu, B. Smart, C. J. Petzold, T. Y. Hsieh, A. Pitcher, J. D. Keasling, and C. R. Bertozzi. 2008. “Membrane proteomics of phagosomes suggests a connection to autophagy.” Proc. Natl. Acad. Sci. USA 105:16952-16957.
- W. Shui, S. A. Gilmore, L. Sheu, J. Liu, J. D. Keasling, and C. R. Bertozzi. 2009. Quantitative proteomic profiling of host-pathogen interactions: the macrophage response to Mycobacterium tuberculosis. J. Proteome Res. 8:282-289.
- J. Kirby and J. D. Keasling. 2009. “Biosynthesis of plant isoprenoids: perspectives for microbial engineering.” Annu. Rev. Plant Biol. 60:335.355.
- Y. J. Tang, W. Shui, S. Myers, X. Feng, C. Bertozzi, J. D. Keasling. 2009. “Central metabolism in Mycobacterium smegmatis during the transition from O(2)-rich to O (2)-poor conditions as studied by isotopomer-assisted metabolite analysis.” Biotechnol. Lett. 31:1233-1240.
- J. E. Dueber, G. C. Wu, G. R. Malmirchegini, T. S. Moon, C. J. Petzold, A. V. Ullal, K. J. Prather, and J. D. Keasling. 2009. “Synthetic protein scaffolds provide modular control over metabolic flux.” Nat. Biotechnol. 27:753-759.
- J. M. Carothers, J. A. Goler, and J. D. Keasling. 2009. “Chemical synthesis using synthetic biology.” Curr. Opin. Biotechnol. 20:498-503.
- J. A. Dietrich, A. E. McKee, and J. D. Keasling. 2010. “High-throughput metabolic engineering: advances in small-molecule screening and selection.” Annu. Rev. Biochem. 79:563-590.
- L. Prach, J. Kirby, J. D. Keasling, T. Alber. 2010. “Diterpene production in Mycobacterium tuberculosis.” FEBS J. 277:3588-3595.
- J. D. Keasling. 2010. “Manufacturing molecules through metabolic engineering.” Science 330:1355-1358.
- W. Shui, C. J. Petzold, A. M. Redding, J. Liu, A. Pitcher, L. Sheu, C. R. Bertozzi, and J. D. Keasling. 2011. “Organelle membrane proteomics reveals differential influence of mycobacterial lipoglycans on macrophage phagosome maturation and autophagosome accumulation.” J. Proteome Res. 10:339-348.
- A. M. Redding-Johanson, T. S. Batth, R. Chan, R. Krupa, H. L. Szmidt, P. D. Adams, J. D. Keasling, T. S. Lee, A. Mukhopadhyay, C. J. Petzold. 2011. “Targeted proteomics for metabolic pathway optimization: application to terpene production.” Metab. Eng. 13:194-203.
- S. M. Ma, D. E. Garcia, A. M. Redding-Johanson, G. D. Friedland, R. Chan, T. S. Batth, J. R. Haliburton, D. Chivian, J. D. Keasling, C. J. Petzold, T. S. Lee, S. R. Chhabra. 2011. “Optimization of a heterologous mevalonate pathway through use of variant HMG-CoA reductases.” Met. Eng. 13:588-597.
- J. D. Keasling. 2012. “Synthetic biology and the development of tools for metabolic engineering.” Met. Eng. 14:189-195.
- S. Yuzawa, W. Kim, L. Katz, and J. D. Keasling. 2012. “Heterologous production of polyketides by modular type I polyketide synthases in Escherichia coli.” Curr. Opin. Biotechnol. 23:725-735.
- J. D. Keasling, A. Mendoza, and P. S. Baran. 2012. “Synthesis: A constructive debate.” Nature 492:188-189.
- J. D. Keasling. 2012. “Engineering biology for drugs and fuels.” Proc. Amer. Philosoph. Soc. 156:283-294.
- S. Yuzawa, N. Chiba, L. Katz, and J. D. Keasling. 2012. “Construction of a part of a 3-hydroxypropionate cycle for heterologous polyketide biosynthesis in Escherichia coli.” Biochemistry 51:9779-9781.
- S. Yuzawa, C. Eng, L. Katz, and J. D. Keasling. 2013. “Broad substrate specificity of the loading didomain of the lipomycin polyketide synthase.” Biochemistry 52:3791-3793.
- S. Yuzawa, C. H. Eng, L. Katz, and J. D. Keasling. 2014. “Enzyme analysis of the polyketide synthase leads to the discovery of a novel analog of the antibiotic a-lipomycin.” J. Antibiotics 67:199-201.
- S. Poust, I. Yoon, P. D. Adams, L. Katz, C. J. Petzold, and J. D. Keasling. 2014. “Understanding the role of histidine in the GHSxG acyltransferase active site motif: evidence for histidine stabilization of the malonyl-enzyme intermediate.” PLoS One 9(10):e109421 doi:10.1371/journal.pone.0109421.
- A. Hagen, S. Poust, T. de Rond, S. Yuzawa, L. Katz, P. D. Adams, C. J. Petzold, and J. D. Keasling. 2014. “In vitro analysis of carboxyacyl substrate tolerance in the loading and first extension modules of Borrelidin polyketide synthase.” Biochemistry 53:5975-5977.