The objective of this work is to investigate the structure, mechanism of action, and inhibition of three different types of metalloprotein, all of which utilize [4Fe-4S] clusters in catalysis. The reactions catalyzed are reductive dehydroxylations, dehydrations and isomerizations, and all of the proteins are of long-term interest because they are essential for the survival of many pathogens and are not used by humans. The proteins are IspG and IspH, involved in reductive dehydroxylations in isoprenoid biosynthesis;quinolinate synthase (NadA), involved in NAD biosynthesis;and dihydroxyacid dehydratase (DHAD) and isopropylmalate isomerase (LeuCD), involved in amino-acid biosynthesis.
In Aim 1 the first objective is to investigate a previously uncharacterized class of IspHs that are found in many anaerobic bacteria, such as those which cause tetanus and botulism, as well as many which are found in the human microbiome. These proteins are 2-3x larger than most bacterial IspHs and contain an IspH-RPS1 (ribosomal binding protein S1) fusion and might act as iron or oxygen sensors. The second objective is to probe the mechanisms of action of both IspG and IspH by using rapid freeze-quench EPR, calorimetry, site-directed mutagenesis, M?ssbauer, X-ray crystallography, and DFT to characterize reaction intermediates. The third objective is to determine the structures of the 3-domain IspGs and develop novel IspG inhibitors.
Aim 2 involves investigation of NadA, an enzyme whose apo-structure resembles that of IspH but whose structure with its 4Fe-4S cluster is unknown. The objective is to determine its structure and mechanism of action and to develop inhibitors as drug leads (against the organism that causes gastric ulcers and carcinoma).
The third Aim i nvolves two [4Fe-4S] hydratase/isomerases (DHAD and LeuCD). Both are predicted to contain two domains and it appears that there are structural similarities between DHAD, LeuCD, aconitase and fumarase A, a hypothesis we will test. Inhibitors have been reported as herbicides, blocking leucine and other branched chain amino-acid biosynthesis, an effect that with the LeuCD inhibitor is reversed with L- leucine, and M. tuberculosis leuCD knockouts are being developed as TB vaccines, making LeuCD and DHAD potential new drug targets and here, we will develop inhibitors, active in cells, that bind to their [4Fe-4S] clusters.

Public Health Relevance

The project is aimed at understanding the structure and function of a series of metallo-proteins that contain [4Fe-4S] clusters. These proteins are essential for the growth and survival of the organisms that cause tuberculosis, stomach ulcers and malaria but are not used by humans, making them of particular interest as drug targets.

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Research Project (R01)
Project #
2R01GM065307-13
Application #
8758404
Study Section
Macromolecular Structure and Function A Study Section (MSFA)
Program Officer
Anderson, Vernon
Project Start
2002-06-01
Project End
2018-08-31
Budget Start
2014-09-10
Budget End
2015-08-31
Support Year
13
Fiscal Year
2014
Total Cost
$356,850
Indirect Cost
$131,850
Name
University of Illinois Urbana-Champaign
Department
Chemistry
Type
Schools of Arts and Sciences
DUNS #
041544081
City
Champaign
State
IL
Country
United States
Zip Code
61820
Kim, Meekyum Olivia; Feng, Xinxin; Feixas, Ferran et al. (2015) A Molecular Dynamics Investigation of Mycobacterium tuberculosis Prenyl Synthases: Conformational Flexibility and Implications for Computer-aided Drug Discovery. Chem Biol Drug Des 85:756-69
Han, Xu; Chen, Chun-Chi; Kuo, Chih-Jung et al. (2015) Crystal structures of ligand-bound octaprenyl pyrophosphate synthase from Escherichia coli reveal the catalytic and chain-length determining mechanisms. Proteins 83:37-45
Sinko, William; Wang, Yang; Zhu, Wei et al. (2014) Undecaprenyl diphosphate synthase inhibitors: antibacterial drug leads. J Med Chem 57:5693-701
Guerra, Francisco; Wang, Ke; Li, Jikun et al. (2014) Inhibition of the 4Fe-4S Proteins IspG and IspH: an EPR, ENDOR and HYSCORE Investigation. Chem Sci 5:1642-1649
Li, Kai; Schurig-Briccio, Lici A; Feng, Xinxin et al. (2014) Multitarget drug discovery for tuberculosis and other infectious diseases. J Med Chem 57:3126-39
Wang, Weixue; Oldfield, Eric (2014) Bioorganometallic chemistry with IspG and IspH: structure, function, and inhibition of the [Fe(4)S(4)] proteins involved in isoprenoid biosynthesis. Angew Chem Int Ed Engl 53:4294-310
Liu, Wenting; Feng, Xinxin; Zheng, Yingying et al. (2014) Structure, function and inhibition of ent-kaurene synthase from Bradyrhizobium japonicum. Sci Rep 4:6214
Benaim, Gustavo; Casanova, Paola; Hernandez-Rodriguez, Vanessa et al. (2014) Dronedarone, an amiodarone analog with improved anti-Leishmania mexicana efficacy. Antimicrob Agents Chemother 58:2295-303
Oldfield, Eric; Feng, Xinxin (2014) Resistance-resistant antibiotics. Trends Pharmacol Sci 35:664-74
Chan, Hsiu-Chien; Feng, Xinxin; Ko, Tzu-Ping et al. (2014) Structure and inhibition of tuberculosinol synthase and decaprenyl diphosphate synthase from Mycobacterium tuberculosis. J Am Chem Soc 136:2892-6

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