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Author ORCID Identifier

https://orcid.org/0000-0002-6547-1343

Date Available

3-19-2026

Year of Publication

2026

Document Type

Doctoral Dissertation

Degree Name

Doctor of Philosophy (PhD)

College

Pharmacy

Department/School/Program

Pharmaceutical Sciences

Faculty

Sylvie Garneau-Tsodikova

Faculty

David Feola

Abstract

Natural products (NPs), are the largest source of bioactive compounds in Nature, and are essential to the treatment of human disease. Nearly 50% of drugs approved for use from 1981 to 2019 owe some aspect of their development to NPs, either in terms of their structure, pharmacophore, or mechanism of action. However, NPs are difficult to structurally optimize. Chemoenzymatic methods for NP derivatization have been increasingly seen as practical alternatives to traditional synthetic methods. Prenyltransferases (PTs) are involved in the primary and secondary metabolism of plants, bacteria, and fungi, and they are key enzymes in the biosynthesis of many clinically relevant natural products (NPs). The dimethylallyl tryptophan synthases (DMATSs) are the best studied class of soluble aromatic PTs with over 50 having been identified and characterized. In addition to their role as key biosynthetic enzymes in the production of clinically relevant NPs, they have generated significant interest as biocatalysts for latestage

C-H functionalization and chemoenzymatic synthesis of indole-containing compounds. DMATSs are uniquely suited for applications as biocatalysts due to their unusually wide substrate scopes, and have been shown repeatedly to act on non-natural substrates with significant structural differences to their natural substrates. Research into the most promising subtype of DMATSs for chemoenzymatic synthesis of diverse molecular scaffolds, the diketopiperazine (DKP)-prenylating DMATSs, has been limited. Repetitive use of indole DKPs modified at the same position, as well as limited test sets of other molecular scaffolds, while valuable, has left many of these enzymes underexplored. Toward gaining further insight into these fascinating enzymes, we sought to probe a previously unexplored region of the binding pocket of the DKP DMATS, FtmPT1. To explore FtmPT1, we synthesized a library of 40 indole DKPs functionalized with sterically and electronically diverse hydrazone moieties at N1 of the DKP ring, over half of which were prenylated by FtmPT1. Our substrate screening revealed that the binding pocket of FtmPT1 was amenable to both halogen and hydrogen bonding. Furthermore, we demonstrated that halogen bonding could be leveraged to change both the prenylation position and type at the indole ring from C2-regular to N1-reverse.

Digital Object Identifier (DOI)

https://doi.org/10.13023/etd.2026.26

Archival?

Archival

Funding Information

This study was supported by the National Science Foundation Graduate Research Fellowship (award no. 2239063) to Evan Miller in 2021.

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