Many biologically active natural products derive their activity from the sugar components of their structures. Changing the structures of these sugars can have a profound impact on the biological activity, selectivity, and pharmacokinetic properties of the parent compounds. This observation has fueled the development of methods to derivatize natural products with diverse sugar moieties by exploiting the sugar biosynthetic machinery. Fully realizing the potential of such an approach relies on the discovery of new sugar biosynthetic pathways, and also requires a thorough understanding of the biosynthetic pathway of each target sugar including detailed mechanistic knowledge of the key enzymes. With these goals in mind, we have produced notable results in work funded by previous grant. As a result of these studies, we have identified four key areas that warrant further investigation in the next funding period. Accordingly, this application outlines experiments designed to learn how desosamine, apiose, kijanose, and 2-deoxy-2- mercaptoglucose are biosynthesized. The specific objectives include (1) mechanistic studies of a radical-SAM enzyme (DesII) involved in the biosynthesis of desosamine, an essential component of many macrolide antibiotics, (2) a determination of the mechanism of the pyranose-to-furanose ring-contraction catalyzed by UDP-apiose synthase, (3) an investigation into the biosynthesis of the unusual nitrosugar moiety (kijanose) of kijanimicin, and (4) the elucidation of the mechanism of sulfur incorporation into the 2-deoxy-2-mercaptoglucose moiety of the antibiotic BE-7585A. The proposed experiments will not only delineate the biosynthesis of deoxy-, branched-chain, nitro-, and sulfur-containing sugars, but will also advance the field of mechanistic enzymology by enhancing our understanding of several important classes of enzymes. Our results should also be valuable to applied biomedical research, as new glycosylation tools (i.e., sugar biosynthetic pathways and enzymes) will be discovered for future secondary metabolite glycodiversification efforts.

Public Health Relevance

Outlined in this application are experiments designed to study the mechanism of the radical SAM enzyme, DesII, involved in the C4-deoxygenation step in desosamine biosynthesis, the mechanism of the ring contraction reaction catalyzed by UDP-apiose synthase (Axs1), the biosynthesis of an unusual nitrosugar, kijanose, and the mechanism of sulfur incorporation into the thiosugar moiety of BE-7585A. The results are expected to significantly advance the field of mechanistic enzymology and should also be valuable to applied biomedical research, as new sugar biosynthetic pathways and enzymes will be discovered for future secondary metabolite glycodiversification efforts.

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Research Project (R01)
Project #
5R01GM035906-26
Application #
7768454
Study Section
Macromolecular Structure and Function E Study Section (MSFE)
Program Officer
Gerratana, Barbara
Project Start
1986-01-01
Project End
2012-12-31
Budget Start
2010-01-01
Budget End
2010-12-31
Support Year
26
Fiscal Year
2010
Total Cost
$483,567
Indirect Cost
Name
University of Texas Austin
Department
Pharmacology
Type
Schools of Pharmacy
DUNS #
170230239
City
Austin
State
TX
Country
United States
Zip Code
78712
Lin, Geng-Min; Romo, Anthony J; Liem, Priscilla H et al. (2017) Identification and Interrogation of the Herbicidin Biosynthetic Gene Cluster: First Insight into the Biosynthesis of a Rare Undecose Nucleoside Antibiotic. J Am Chem Soc 139:16450-16453
Kim, Hak Joong; Liu, Yung-Nan; McCarty, Reid M et al. (2017) Reaction Catalyzed by GenK, a Cobalamin-Dependent Radical S-Adenosyl-l-methionine Methyltransferase in the Biosynthetic Pathway of Gentamicin, Proceeds with Retention of Configuration. J Am Chem Soc 139:16084-16087
Ko, Yeonjin; Wang, Shao-An; Ogasawara, Yasushi et al. (2017) Identification and Characterization of Enzymes Catalyzing Pyrazolopyrimidine Formation in the Biosynthesis of Formycin A. Org Lett 19:1426-1429
Bridwell-Rabb, Jennifer; Zhong, Aoshu; Sun, He G et al. (2017) A B12-dependent radical SAM enzyme involved in oxetanocin A biosynthesis. Nature 544:322-326
Lin, Chia-I; McCarty, Reid M; Liu, Hung-Wen (2017) The Enzymology of Organic Transformations: A Survey of Name Reactions in Biological Systems. Angew Chem Int Ed Engl 56:3446-3489
Lin, Geng-Min; Sun, He G; Liu, Hung-Wen (2016) Study of Uridine 5'-Diphosphate (UDP)-Galactopyranose Mutase Using UDP-5-Fluorogalactopyranose as a Probe: Incubation Results and Mechanistic Implications. Org Lett 18:3438-41
Ushimaru, Richiro; Lin, Chia-I; Sasaki, Eita et al. (2016) Characterization of Enzymes Catalyzing Transformations of Cysteine S-Conjugated Intermediates in the Lincosamide Biosynthetic Pathway. Chembiochem 17:1606-11
Jackson, David R; Yu, Xia; Wang, Guojung et al. (2016) Insights into Complex Oxidation during BE-7585A Biosynthesis: Structural Determination and Analysis of the Polyketide Monooxygenase BexE. ACS Chem Biol 11:1137-47
Kim, Hak Joong; LeVieux, Jake; Yeh, Yu-Cheng et al. (2016) C3'-Deoxygenation of Paromamine Catalyzed by a Radical S-Adenosylmethionine Enzyme: Characterization of the Enzyme AprD4 and Its Reductase Partner AprD3. Angew Chem Int Ed Engl 55:3724-8
Bridwell-Rabb, Jennifer; Kang, Gyunghoon; Zhong, Aoshu et al. (2016) An HD domain phosphohydrolase active site tailored for oxetanocin-A biosynthesis. Proc Natl Acad Sci U S A 113:13750-13755

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