# Structural Biology of Complex Enzymes

> **NIH NIH R01** · UNIVERSITY OF MICHIGAN AT ANN ARBOR · 2024 · $417,926

## Abstract

Project Summary
Natural product biosynthetic pathways harbor a vast synthetic potential for chemical groups that are rare
in biology. Enzymes that were adapted from primary metabolism to novel functions in these secondary-
metabolite pathways are a major source biocatalytic potential for many applications. In this project, the
structure and function of several enzymes that catalyze unusual reactions in the biosynthesis of natural
products will be investigated. Protein crystal structures will inform the development of functional assays,
which will be used to test structure-based hypotheses about mechanism, substrate selectivity and product
specificity. The enzymes are from bacterial and fungal biosynthetic pathways for several natural product
classes, including polyketides, nonribosomal peptides and azaphilones. The four enzyme systems have
great potential for biocatalyst development within or outside their natural pathways, for advancing our
understanding of protein evolution in nature, for expanding the scope of enzyme chemistry, and for
engineering new function. In the first system, a bacterial enzyme has distinct acyl transfer and
decarboxylation functions in two biosynthetic pathways. The dual functions are represented on widely
separated branches of the larger superfamily; how they are combined in one enzyme will be determined.
In the second system, an enzyme family related to oxidoreductases functions in offloading an amide
product from the carrier protein of a nonribosomal peptide synthetase. In the third system, a large family
of fungal flavin-dependent monooxygenases catalyzes hydroxylation reactions on aromatic substrates in
azaphilone and related pathways. The structural basis for the site- and stereo-specificity of selected
family members will be determined in order to develop a panel of biocatalysts for challenging
dearomatization reactions. In the fourth system, the determinants of macrocycle formation and the
possibilities for an expanded substrate scope of five enzymes will be investigated.

## Key facts

- **NIH application ID:** 10846572
- **Project number:** 5R01DK042303-34
- **Recipient organization:** UNIVERSITY OF MICHIGAN AT ANN ARBOR
- **Principal Investigator:** JANET L. SMITH
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2024
- **Award amount:** $417,926
- **Award type:** 5
- **Project period:** 1990-02-01 → 2026-05-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10846572

## Citation

> US National Institutes of Health, RePORTER application 10846572, Structural Biology of Complex Enzymes (5R01DK042303-34). Retrieved via AI Analytics 2026-05-24 from https://api.ai-analytics.org/grant/nih/10846572. Licensed CC0.

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