M. tuberculosis (Mtb), a global health crisis and bioterrorism threat, is increasingly drug-resistant, but little new chemotherapy has emerged in decades. A fresh approach to chemotherapy is to target pathways essential for the pathogen to survive in its metabolic niche in host macrophages. This application is based on the hypothesis that Mtb requires 3 enzymes to survive under energy-poor, oxidative and nitrosative conditions in the phagosome: (1) Lipoamide dehydrogenase (Lpd) serves in pyruvate dehydrogenase and probably in branched chain ketoacid dehydrogenase as well as in peroxynitrite reductase /peroxidase and thus is key for net synthesis of acyl CoA's, the precursors of fatty acids, and for resistance to reactive nitrogen intermediates (RNI). (2) a-ketoglutarate (KG) decarboxylase (KDC) converts KG to succinic semialdehyde (SSA), replacing KG dehydrogenase, which Mtb lacks. SSA dehydrogenase converts SSA to succinate and may thereby connect the oxidative and reductive limbs of Mtb's citric acid cycle (CAC). KDC may therefore be important for Mtb's generation of energy, reducing equivalents, amino acids and heme. (3) Ultraviolet repair (Uvr) B, part of the nucleotide excision repair pathway, was found by saturation transposon mutagenesis to be essential for Mtb to survive RNI and to kill mice. KDC and UvrB lack human homologs, and Lpd's crystal structure shows key differences from the human enzyme. We will use allelic replacement to disrupt the 3 genes encoding these enzymes, or establish their essentiality; use conventional and novel combinatorial libraries to identify chemical inhibitors of each enzyme; analyze the crystal structures of Lpd and KDC with and without inhibitors; and assess these enzymes as potential targets for new chemotherapeutics. Antibiotics to date only target enzymes that synthesize protein, nucleic acids, cell walls and folate. The fundamental novelty of this work is to broaden the range of targets to include enzymes of intermediary metabolism and DNA repair.

Agency
National Institute of Health (NIH)
Institute
National Institute of Allergy and Infectious Diseases (NIAID)
Type
Research Project (R01)
Project #
5R01AI064768-04
Application #
7385159
Study Section
Special Emphasis Panel (ZRG1-DDR (01))
Program Officer
Sizemore, Christine F
Project Start
2005-06-01
Project End
2010-02-28
Budget Start
2008-03-01
Budget End
2009-02-28
Support Year
4
Fiscal Year
2008
Total Cost
$861,514
Indirect Cost
Name
Weill Medical College of Cornell University
Department
Microbiology/Immun/Virology
Type
Schools of Medicine
DUNS #
060217502
City
New York
State
NY
Country
United States
Zip Code
10065
Nathan, Carl; Barry 3rd, Clifton E (2015) TB drug development: immunology at the table. Immunol Rev 264:308-18
Maksymiuk, Christina; Ioerger, Thomas; Balakrishnan, Anand et al. (2015) Comparison of transposon and deletion mutants in Mycobacterium tuberculosis: The case of rv1248c, encoding 2-hydroxy-3-oxoadipate synthase. Tuberculosis (Edinb) 95:689-694
Maksymiuk, Christina; Balakrishnan, Anand; Bryk, Ruslana et al. (2015) E1 of ?-ketoglutarate dehydrogenase defends Mycobacterium tuberculosis against glutamate anaplerosis and nitroxidative stress. Proc Natl Acad Sci U S A 112:E5834-43
Nathan, Carl (2015) What can immunology contribute to the control of the world's leading cause of death from bacterial infection? Immunol Rev 264:2-5
Bryk, Ruslana; Arango, Nancy; Maksymiuk, Christina et al. (2013) Lipoamide channel-binding sulfonamides selectively inhibit mycobacterial lipoamide dehydrogenase. Biochemistry 52:9375-84
Balakrishnan, Anand; Jordan, Frank; Nathan, Carl F (2013) Influence of allosteric regulators on individual steps in the reaction catalyzed by Mycobacterium tuberculosis 2-hydroxy-3-oxoadipate synthase. J Biol Chem 288:21688-702
Nathan, Carl (2012) Fresh approaches to anti-infective therapies. Sci Transl Med 4:140sr2
Mazloum, Nayef; Stegman, Melanie A; Croteau, Deborah L et al. (2011) Identification of a chemical that inhibits the mycobacterial UvrABC complex in nucleotide excision repair. Biochemistry 50:1329-35
Venugopal, Aditya; Bryk, Ruslana; Shi, Shuangping et al. (2011) Virulence of Mycobacterium tuberculosis depends on lipoamide dehydrogenase, a member of three multienzyme complexes. Cell Host Microbe 9:21-31
de Carvalho, Luiz Pedro S; Ling, Yan; Shen, Chun et al. (2011) On the chemical mechanism of succinic semialdehyde dehydrogenase (GabD1) from Mycobacterium tuberculosis. Arch Biochem Biophys 509:90-9

Showing the most recent 10 out of 15 publications