Researches in my laboratory illustrate the principles, concepts and practices of molecular genetics to solve the biochemical and biological problems. Our major theme is to look into the compilation of bioactive metabolites and related natural products. These studies work out with a coalition of genetic, chemical and biochemical approaches to explore the metabolic pathways, characterize the genetic and biochemical machinery, and apply this knowledge to tackle the novel bioactive compounds.
The primary targets of our studies are the ansamitocin, an extremely potent but also very toxic antitumor agent with a potential clinical interest; the ansamycin antibiotics rifamycin, a clinically important antitubercular drug; the manumycin antibiotics, which are potent, selective and competitive Ras farnesyltransferase inhibitors; the pyocyanin metabolites which show a range of interesting biological activities including as a vital virulence factor in pathogen infection.
The genetic approaches involve the cloning, mutational analysis and functional expression of biosynthetic genes. In parallel, chemical and biochemical approaches engage a series of isotope-labeled feeding experiments with precursors and intermediates, isolation and structure elucidation of newly accumulated compounds from the purposely-designated mutants, and the characterization and mechanistic analysis of these vital metabolic enzymes. The well-elucidated biosynthetic pathway can prompt a new series of spanking products with novel structures followed by reengineering the critical biosynthetic gene components to fiddle with the intrinsic catalytic specificity.
P. Spiteller, L. Bai, G. Shang, B. J. Carroll, T. -W. Yu, H. G. Floss The post-polyketide synthase modification steps in the biosynthesis of the antitumor agent ansamitocin by Actinosynnema pretiosum. J Am Chem Soc. 125, 14236-7 (2003)..
T. -W. Yu, L. Bai, D. Clade, D. Hoffmann, S. Toelzer, K. Q. Trinh, J. Xu, S. J. Moss, E. Leistner, H. G. Floss The biosynthetic gene cluster of the maytansinoid antitumor agent ansamitocin from Actinosynnema pretiosum. Proc Natl Acad Sci U S A. 99, 7968-73 (2002).
B. J. Carroll, S. J. Moss, L. Bai, Y Kato, S. Toelzer, T. -W. Yu, H. G. Floss Identification of a set of genes involved in the formation of the substrate for the incorporation of the unusual "glycolate" chain extension unit in ansamitocin biosynthesis. J Am Chem Soc. 124, 4176-7 (2002).
Y. Kato, L. Bai, Q. Xue, W. P. Revill, T. -W. Yu, H. G. Floss 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. J Am Chem Soc 124, 5268-9 (2002).
K. Arakawa, R. Müller, T. Mahmud, T. -W. Yu, H. G. Floss Characterization of the early stage aminoshikimate pathway in the formation of 3-amino-5-hydroxybenzoic acid: the RifN protein specifically converts kanosamine into kanosamine 6-phosphate. J Am Chem Soc. 124, 10644-5 (2002).
T. -W. Yu, R. Müller, M. Müller, X. Zhang, G. Draeger, C. -G. Kim, E. Leistner, H. G. Floss Mutational analysis and reconstituted expression of the biosynthetic genes involved in the formation of 3-amino-5-hydroxybenzoic acid, the starter unit of rifamycin biosynthesis in Amycolatopsis mediterranei S699. J Biol Chem. 276, 12546-55 (2001).
T.-W. Yu, Y. Shen, Y. Doi-Katayama, L. Tang, C. Park, B. S. Moore, C. R. Hutchinson, H. G. Floss “Direct evidence that the rifamycin polyketide synthase assembles polyketide chains processively”, Proc. Nat. Acad. Sci. USA 96, 9051-9056 (1999).
J. C. Eads, M. Beeby, G. Scapin, T.-W. Yu, H. G. Floss “The Crystal Structure of 3-Amino-5-hydroxybenzoic Acid (AHBA) Synthase”, Biochemistry 38, 9840-9849 (1999).
Y. Shen, P. Yoon, T.-W. Yu, H. G. Floss, David Hopwood, B. S. Moore “Ectopic Expression of the Minimal whiE Polyketide Synthase Generates a Library of Aromatic Polyketides of Diverse Sizes and Shapes”, Proc. Nat. Acad. Sci. USA 96, 3622-3627 (1999).