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
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Hai, Yang; Edwards, Jennifer E; Van Zandt, Michael C et al. (2014) Crystal structure of Schistosoma mansoni arginase, a potential drug target for the treatment of schistosomiasis. Biochemistry 53:4671-84
D'Antonio, Edward L; Ullman, Buddy; Roberts, Sigrid C et al. (2013) Crystal structure of arginase from Leishmania mexicana and implications for the inhibition of polyamine biosynthesis in parasitic infections. Arch Biochem Biophys 535:163-76
Genshaft, Alexander; Moser, Joe-Ann S; D'Antonio, Edward L et al. (2013) Energetically unfavorable amide conformations for N6-acetyllysine side chains in refined protein structures. Proteins 81:1051-7
Decroos, Christophe; Bowman, Christine M; Christianson, David W (2013) Synthesis and evaluation of Nýýý-acetylspermidine analogues as inhibitors of bacterial acetylpolyamine amidohydrolase. Bioorg Med Chem 21:4530-40
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Ilies, Monica; Di Costanzo, Luigi; Dowling, Daniel P et al. (2011) Binding of ?,?-disubstituted amino acids to arginase suggests new avenues for inhibitor design. J Med Chem 54:5432-43
D'Antonio, Edward L; Christianson, David W (2011) Crystal structures of complexes with cobalt-reconstituted human arginase I. Biochemistry 50:8018-27
Lombardi, Patrick M; Angell, Heather D; Whittington, Douglas A et al. (2011) Structure of prokaryotic polyamine deacetylase reveals evolutionary functional relationships with eukaryotic histone deacetylases. Biochemistry 50:1808-17

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