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 the arginases and the histone deacetylases (HDACs). The arginases utilize a binuclear Mn(II)-Mn(II) cluster for catalysis, whereas the HDACs utilize a single Zn(II) or Fe(II) ion for catalysis. Unexpectedly, these two enzyme families are evolutionarily related and share a common three-dimensional fold despite insignificant amino acid sequence identity and divergent metal ion stoichiometry and selectivity. Increased arginase activity is implicated in cardiovascular disease, asthma, cancer, and parasitic infections, and increased HDAC activity is found in cancer. Both metalloenzymes are validated targets for structure-based drug design. Furthermore, decreased HDAC8 activity is found in Cornelia de Lange Syndrome (CdLS), a congenital birth defect that occurs in one out of 10,000 births. Accordingly, HDAC8 mutants responsible for decreased activity are potential therapeutic targets for molecular activators that can restore normal biological function. To advance our understanding of structure-function relationships in the arginase-deacetylase fold, and to enable innovative molecular approaches for new disease therapies, we will pursue the following lines of investigation: (1) We will fully characterize the reaction kinetics and determine X-ray crystal structures of HDAC8 mutants identified in CdLS. These studies will provide the first molecular view of compromised HDAC8 catalysis underlying the birth defect. Additionally, we will evaluate the ability of molecular activators to restore normal catalytic function in these mutants, and we will determine X-ray crystal structures of HDAC8-activator complexes to delineate their mode of action. (2) We will determine X-ray crystal structures of mutationally inactivated HDAC8 complexed with peptide and/or protein substrates to understand the structural basis of substrate recognition and catalysis. These structures may reveal how some CdLS HDAC8 mutants perturb the enzyme-substrate interface. (3) Finally, we will establish structure-function relationships for parasitic arginases to guide the design of species-specific arginase inhibitors, and we will explore the ability of selected inhibitors to block polyamine biosynthesis in parasites We will also characterize the arginase-like metalloenzyme from Trypanosoma cruzi, which catalyzes an unusual reaction of histidine catabolism.

Public Health Relevance

This research program explores molecular approaches for the study and regulation of aberrant metalloenzyme activity in human disease, focusing on the structural and chemical biology of arginases and histone deacetylases (HDACs). Increased arginase activity is implicated in cardiovascular disease, asthma, cancer, and parasitic infections; the structure-based design of arginase inhibitors will lead to new therapeutic strategies for treating these diseases. Certain mutations in HDAC8 decrease enzyme activity and cause Cornelia de Lange Syndrome, a congenital birth defect; understanding structure-function relationships in HDAC8 mutants will reveal the molecular basis of the birth defect and guide the development of activators that can rescue catalysis.

National Institute of Health (NIH)
National Institute of General Medical Sciences (NIGMS)
Research Project (R01)
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Macromolecular Structure and Function A Study Section (MSFA)
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Smith, Ward
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University of Pennsylvania
Schools of Arts and Sciences
United States
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Porter, Nicholas J; Wagner, Florence F; Christianson, David W (2018) Entropy as a Driver of Selectivity for Inhibitor Binding to Histone Deacetylase 6. Biochemistry 57:3916-3924
Bhatia, Sanil; Krieger, Viktoria; Groll, Michael et al. (2018) Discovery of the First-in-Class Dual Histone Deacetylase-Proteasome Inhibitor. J Med Chem 61:10299-10309
Porter, Nicholas J; Osko, Jeremy D; Diedrich, Daniela et al. (2018) Histone Deacetylase 6-Selective Inhibitors and the Influence of Capping Groups on Hydroxamate-Zinc Denticity. J Med Chem 61:8054-8060
Mackwitz, Marcel K W; Hamacher, Alexandra; Osko, Jeremy D et al. (2018) Multicomponent Synthesis and Binding Mode of Imidazo[1,2- a]pyridine-Capped Selective HDAC6 Inhibitors. Org Lett 20:3255-3258
Shinsky, Stephen A; Christianson, David W (2018) Polyamine Deacetylase Structure and Catalysis: Prokaryotic Acetylpolyamine Amidohydrolase and Eukaryotic HDAC10. Biochemistry 57:3105-3114
Porter, Nicholas J; Mahendran, Adaickapillai; Breslow, Ronald et al. (2017) Unusual zinc-binding mode of HDAC6-selective hydroxamate inhibitors. Proc Natl Acad Sci U S A 114:13459-13464
Hai, Yang; Shinsky, Stephen A; Porter, Nicholas J et al. (2017) Histone deacetylase 10 structure and molecular function as a polyamine deacetylase. Nat Commun 8:15368
Bitler, Benjamin G; Wu, Shuai; Park, Pyoung Hwa et al. (2017) ARID1A-mutated ovarian cancers depend on HDAC6 activity. Nat Cell Biol 19:962-973
Porter, Nicholas J; Christianson, David W (2017) Binding of the Microbial Cyclic Tetrapeptide Trapoxin A to the Class I Histone Deacetylase HDAC8. ACS Chem Biol 12:2281-2286
Gantt, Sister M Lucy; Decroos, Christophe; Lee, Matthew S et al. (2016) General Base-General Acid Catalysis in Human Histone Deacetylase 8. Biochemistry 55:820-32

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