THPP target assignment reveals EchA6 as an essential fatty acid shuttle in mycobacteria

DOI: 10.1038/nmicrobiol.2015.6

Authors: Jonathan A. G. Cox (University of Birmingham) , Katherine A. Abrahams (University of Birmingham) , Carlos Alemparte (GlaxoSmithKline) , Sonja Ghidelli-Disse (Cellzome, Meyerhofstrasse 1) , Joaquín Rullas (GlaxoSmithKline) , Iñigo Angulo-Barturen (GlaxoSmithKline) , Albel Singh (University of Birmingham) , Sudagar S. Gurcha (University of Birmingham) , Vijayashankar Nataraj (University of Birmingham) , Stephen Bethell (University of Birmingham) , Modesto J. Remuiñán (GlaxoSmithKline) , Lourdes Encinas (GlaxoSmithKline) , Peter J. Jervis (University of Birmingham) , Nicholas C. Cammack (GlaxoSmithKline) , Apoorva Bhatt (University of Birmingham) , Ulrich Kruse (Cellzome, Meyerhofstrasse 1) , Marcus Bantscheff (Cellzome, Meyerhofstrasse 1) , Klaus Fütterer (University of Birmingham) , David Barros (GlaxoSmithKline) , Lluis Ballell (GlaxoSmithKline) , Gerard Drewes (Cellzome, Meyerhofstrasse 1) , Gurdyal S. Besra (University of Birmingham)
Co-authored by industrial partner: Yes

Type: Journal Paper
Journal: Nature Microbiology , VOL 1

State: Published (Approved)
Published: February 2016
Diamond Proposal Number(s): 8359 , 10369

Abstract: Phenotypic screens for bactericidal compounds against drug-resistant tuberculosis are beginning to yield novel inhibitors. However, reliable target identification remains challenging. Here, we show that tetrahydropyrazo[1,5-a]pyrimidine-3-carboxamide (THPP) selectively pulls down EchA6 in a stereospecific manner, instead of the previously assigned target Mycobacterium tuberculosis MmpL3. While homologous to mammalian enoyl-coenzyme A (CoA) hydratases, EchA6 is non-catalytic yet essential and binds long-chain acyl-CoAs. THPP inhibitors compete with CoA-binding, suppress mycolic acid synthesis, and are bactericidal in a mouse model of chronic tuberculosis infection. A point mutation, W133A, abrogated THPP-binding and increased both the in vitro minimum inhibitory concentration and the in vivo effective dose 99 in mice. Surprisingly, EchA6 interacts with selected enzymes of fatty acid synthase II (FAS-II) in bacterial two-hybrid assays, suggesting essentiality may be linked to feeding long-chain fatty acids to FAS-II. Finally, our data show that spontaneous resistance-conferring mutations can potentially obscure the actual target or alternative targets of small molecule inhibitors.

Journal Keywords: Mycobacterium tuberculosis, mycolic acid synthesis, pseudo enzyme

Diamond Keywords: Tuberculosis (TB); Bacteria

Subject Areas: Biology and Bio-materials, Chemistry, Medicine


Instruments: I03-Macromolecular Crystallography , I04-1-Macromolecular Crystallography (fixed wavelength) , I04-Macromolecular Crystallography

Added On: 28/03/2016 14:33

Discipline Tags:

Pathogens Antibiotic Resistance Infectious Diseases Health & Wellbeing Biochemistry Chemistry Structural biology Organic Chemistry Drug Discovery Life Sciences & Biotech

Technical Tags:

Diffraction Macromolecular Crystallography (MX)