M. tuberculosis (Mtb) causes latent infections that affect a third of the world's population and active tuberculosis kills two million people every year. Chemotherapy of tuberculosis requires long treatment regimens and is complicated by the emergence of multi-drug resistant and extensively drug resistant Mtb strains. New drugs that shorten TB chemotherapy and cure drug resistant TB are urgently needed. Mtb encounters an acidic pH within phagosomes of interferon-3 activated macrophages and must prevent excessive entry of protons into its cytosol. One pathway important for pH homeostasis and virulence of Mtb depends on the membrane-associated serine hydrolase Rv3671c. The goals of this proposal are to determine the molecular mechanisms by which Rv3671c protects Mtb from intracellular acidification and contributes to virulence.
Our specific aims are: I. To determine why Rv3671c is required for resistant of Mtb against acid. We will investigate the mechanism by which this serine hydrolase controls pH and acid resistance. II. To determine why Rv3671c is required for persistence in activated macrophages and mice. We will investigate if Rv3671c affects phagosome maturation in IFN-3 activated macrophages. We will use genetically altered mice to determine if Rv3671c protects against host defense mechanisms, which act synergistically with phagosome acidification. III. To identify small molecules that interfere with pH homeostasis in Mtb. We will use a high- throughput screen to identify such inhibitors, which will help to investigate the biology of intrabacterial pH homeostasis in Mtb and facilitate the development of new drugs against tuberculosis.

Public Health Relevance

Tuberculosis (TB) is one of the world's most devastating diseases. It is responsible for more than two million deaths and eight million new cases annually. Work outlined in this proposal will investigate virulence mechanisms that allow Mtb to persist within its host and cause disease. It will help identify novel drug targets that might facilitate the development of new drugs against tuberculosis.

Agency
National Institute of Health (NIH)
Institute
National Institute of Allergy and Infectious Diseases (NIAID)
Type
Research Project (R01)
Project #
5R01AI081725-05
Application #
8436296
Study Section
Host Interactions with Bacterial Pathogens Study Section (HIBP)
Program Officer
Lacourciere, Karen A
Project Start
2009-03-01
Project End
2014-02-28
Budget Start
2013-03-01
Budget End
2014-02-28
Support Year
5
Fiscal Year
2013
Total Cost
$513,196
Indirect Cost
$198,225
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
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Darby, Crystal M; Ingolfsson, Helgi I; Jiang, Xiuju et al. (2013) Whole cell screen for inhibitors of pH homeostasis in Mycobacterium tuberculosis. PLoS One 8:e68942
de Carvalho, Luiz Pedro S; Darby, Crystal M; Rhee, Kyu Y et al. (2011) Nitazoxanide Disrupts Membrane Potential and Intrabacterial pH Homeostasis of Mycobacterium tuberculosis. ACS Med Chem Lett 2:849-854
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Biswas, Tapan; Small, Jennifer; Vandal, Omar et al. (2010) Structural insight into serine protease Rv3671c that Protects M. tuberculosis from oxidative and acidic stress. Structure 18:1353-63
Ehrt, Sabine; Schnappinger, Dirk (2009) Mycobacterial survival strategies in the phagosome: defence against host stresses. Cell Microbiol 11:1170-8