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Title: Identification and Characterization of an Allosteric Inhibitory Site on Dihydropteroate Synthase

Authors:
; ; ; ; ; ; ; ; ;  [1];  [2]
  1. (Tennessee-M)
  2. (
Publication Date:
Research Org.:
Argonne National Lab. (ANL), Argonne, IL (United States). Advanced Photon Source (APS)
Sponsoring Org.:
OTHERNIH
OSTI Identifier:
1140253
Resource Type:
Journal Article
Resource Relation:
Journal Name: ACS Chem. Biol.; Journal Volume: 9; Journal Issue: (6) ; 06, 2014
Country of Publication:
United States
Language:
ENGLISH

Citation Formats

Hammoudeh, Dalia I., Daté, Mihir, Yun, Mi-Kyung, Zhang, Weixing, Boyd, Vincent A., Follis, Ariele Viacava, Griffith, Elizabeth, Lee, Richard E., Bashford, Donald, White, Stephen W., and SJCH). Identification and Characterization of an Allosteric Inhibitory Site on Dihydropteroate Synthase. United States: N. p., 2014. Web. doi:10.1021/cb500038g.
Hammoudeh, Dalia I., Daté, Mihir, Yun, Mi-Kyung, Zhang, Weixing, Boyd, Vincent A., Follis, Ariele Viacava, Griffith, Elizabeth, Lee, Richard E., Bashford, Donald, White, Stephen W., & SJCH). Identification and Characterization of an Allosteric Inhibitory Site on Dihydropteroate Synthase. United States. doi:10.1021/cb500038g.
Hammoudeh, Dalia I., Daté, Mihir, Yun, Mi-Kyung, Zhang, Weixing, Boyd, Vincent A., Follis, Ariele Viacava, Griffith, Elizabeth, Lee, Richard E., Bashford, Donald, White, Stephen W., and SJCH). Thu . "Identification and Characterization of an Allosteric Inhibitory Site on Dihydropteroate Synthase". United States. doi:10.1021/cb500038g.
@article{osti_1140253,
title = {Identification and Characterization of an Allosteric Inhibitory Site on Dihydropteroate Synthase},
author = {Hammoudeh, Dalia I. and Daté, Mihir and Yun, Mi-Kyung and Zhang, Weixing and Boyd, Vincent A. and Follis, Ariele Viacava and Griffith, Elizabeth and Lee, Richard E. and Bashford, Donald and White, Stephen W. and SJCH)},
abstractNote = {},
doi = {10.1021/cb500038g},
journal = {ACS Chem. Biol.},
number = (6) ; 06, 2014,
volume = 9,
place = {United States},
year = {Thu Jul 03 00:00:00 EDT 2014},
month = {Thu Jul 03 00:00:00 EDT 2014}
}
  • HIV integrase (IN) is an essential enzyme in HIV replication and an important target for drug design. IN has been shown to interact with a number of cellular and viral proteins during the integration process. Disruption of these important interactions could provide a mechanism for allosteric inhibition of IN. We present the highest resolution crystal structure of the IN core domain to date. We also present a crystal structure of the IN core domain in complex with sucrose which is bound at the dimer interface in a region that has previously been reported to bind integrase inhibitors.
  • Dihydropteroate synthase (DHPS) is a key enzyme in bacterial folate synthesis and the target of the sulfonamide class of antibacterials. Resistance and toxicities associated with sulfonamides have led to a decrease in their clinical use. Compounds that bind to the pterin binding site of DHPS, as opposed to the p-amino benzoic acid (pABA) binding site targeted by the sulfonamide agents, are anticipated to bypass sulfonamide resistance. To identify such inhibitors and map the pterin binding pocket, we have performed virtual screening, synthetic, and structural studies using Bacillus anthracis DHPS. Several compounds with inhibitory activity have been identified, and crystal structuresmore » have been determined that show how the compounds engage the pterin site. The structural studies identify the key binding elements and have been used to generate a structure-activity based pharmacophore map that will facilitate the development of the next generation of DHPS inhibitors which specifically target the pterin site.« less
  • The sulfonamide antibiotics inhibit dihydropteroate synthase (DHPS), a key enzyme in the folate pathway of bacteria and primitive eukaryotes. However, resistance mutations have severely compromised the usefulness of these drugs. We report structural, computational, and mutagenesis studies on the catalytic and resistance mechanisms of DHPS. By performing the enzyme-catalyzed reaction in crystalline DHPS, we have structurally characterized key intermediates along the reaction pathway. Results support an S{sub N}1 reaction mechanism via formation of a novel cationic pterin intermediate. We also show that two conserved loops generate a substructure during catalysis that creates a specific binding pocket for p-aminobenzoic acid, onemore » of the two DHPS substrates. This substructure, together with the pterin-binding pocket, explains the roles of the conserved active-site residues and reveals how sulfonamide resistance arises.« less
  • Dihydropteroate synthase (DHPS) is the validated drug target for sulfonamide antimicrobial therapy. However, due to widespread drug resistance and poor tolerance, the use of sulfonamide antibiotics is now limited. The pterin binding pocket in DHPS is highly conserved and is distinct from the sulfonamide binding site. It therefore represents an attractive alternative target for the design of novel antibacterial agents. We previously carried out the structural characterization of a known pyridazine inhibitor in the Bacillus anthracis DHPS pterin site and identified a number of unfavorable interactions that appear to compromise binding. With this structural information, a series of 4,5-dioxo-1,4,5,6-tetrahydropyrimido[4,5-c]pyridazines weremore » designed to improve binding affinity. Most importantly, the N-methyl ring substitution was removed to improve binding within the pterin pocket, and the length of the side chain carboxylic acid was optimized to fully engage the pyrophosphate binding site. These inhibitors were synthesized and evaluated by an enzyme activity assay, X-ray crystallography, isothermal calorimetry, and surface plasmon resonance to obtain a comprehensive understanding of the binding interactions from structural, kinetic, and thermodynamic perspectives. This study clearly demonstrates that compounds lacking the N-methyl substitution exhibit increased inhibition of DHPS, but the beneficial effects of optimizing the side chain length are less apparent.« less