# Structure and Function of Metalloenzymes

> **NIH NIH R01** · UNIVERSITY OF PENNSYLVANIA · 2022 · $385,047

## Abstract

The proposed research explores molecular approaches for the study and regulation of aberrant
metalloenzyme activity in human disease, focusing on the structural and chemical biology of histone
deacetylase (HDAC) isozymes 6, 8, 10, and 11. These zinc-dependent enzymes are targets for drug design
efforts aimed at developing new approaches to cancer chemotherapy, treatment of neurodegenerative
disease, and immune modulation. To advance our understanding of structure and function in this important
family of metalloenzymes, and to enable innovative molecular approaches for new disease therapies, we aim
to pursue the following lines of investigation:
 (1) We propose to determine crystal structures of HDAC6 complexed with fluorinated inhibitors to probe the
medicinal chemistry of a fluorophilic crevice in the enzyme active site. These studies will also inform optimal
approaches for the development of 18F derivatives used in PET imaging of HDAC6 and other proteins. We will
also determine structures of complexes with large macrocyclic octapeptide and nonapeptide inhibitors that will
map out interactions in the outer active site cleft. Analysis of these complexes will illuminate structural features
in the outer active site cleft that also accommodate the binding of large protein substrates. Finally, we will
explore the preparation and structure determination of a ternary complex of HDAC6, the E3 ubiquitin ligase
protein cereblon, and a proteolysis-targeting chimera (PROTAC).
 (2) We propose to explore the structural basis of HDAC10 substrate specificity to better understand the
cryptic lysine deacetylase activity observed for this polyamine deacetylase. The binding of acetyllysine-
containing substrates must require conformational changes in the active site to switch between the binding of
bulky peptide and protein substrates versus slender polyamine substrates. Additionally, we will determine
crystal structures of complexes with HDAC10-selective inhibitors containing mercaptoacetamide zinc-binding
groups. In view of the genotoxicity associated with degradation of the hydroxamate moiety, HDAC inhibitors
are needed with alternative zinc-binding groups that exhibit improved stability and safety profiles. Finally, we
will explore the preparation and structure determination of a ternary HDAC10-PROTAC-cereblon complex.
 (3) We propose to study the structural basis of the lysine-fatty acid deacylase activity of HDAC8 and
HDAC11. We will determine the structure of an intact enzyme-substrate complex with HDAC8 to map out the
fatty acid binding site. We will also explore the crystallization and structure determination of the sole class IV
isozyme, HDAC11, which represents the last frontier of HDAC structural biology. We aim to bring the same
rigor of structure-function analysis to this isozyme as we have brought to other HDAC isozymes in recent
years.

## Key facts

- **NIH application ID:** 10435635
- **Project number:** 2R01GM049758-28
- **Recipient organization:** UNIVERSITY OF PENNSYLVANIA
- **Principal Investigator:** DAVID W CHRISTIANSON
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2022
- **Award amount:** $385,047
- **Award type:** 2
- **Project period:** 1994-05-01 → 2026-03-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10435635

## Citation

> US National Institutes of Health, RePORTER application 10435635, Structure and Function of Metalloenzymes (2R01GM049758-28). Retrieved via AI Analytics 2026-05-23 from https://api.ai-analytics.org/grant/nih/10435635. Licensed CC0.

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