Identification of Chemical Scaffolds That Inhibit the Mycobacterium tuberculosis Respiratory Complex Succinate Dehydrogenase.

Drug-resistant Mycobacterium tuberculosis is a significant cause of infectious disease morbidity and mortality for which new antimicrobials are urgently needed. Inhibitors of mycobacterial respiratory energy metabolism have emerged as promising next-generation antimicrobials, but a number of targets remain unexplored. Succinate dehydrogenase (SDH), a focal point in mycobacterial central carbon metabolism and respiratory energy production, is required for growth and survival in M. tuberculosis under a number of conditions, highlighting the potential of inhibitors targeting mycobacterial SDH enzymes. To advance SDH as a novel drug target in M. tuberculosis, we utilized a combination of biochemical screening and in-silico deep learning technologies to identify multiple chemical scaffolds capable of inhibiting mycobacterial SDH activity. Antimicrobial susceptibility assays show that lead inhibitors are bacteriostatic agents with activity against wild-type and drug-resistant strains of M. tuberculosis. Mode of action studies on lead compounds demonstrate that the specific inhibition of SDH activity dysregulates mycobacterial metabolism and respiration and results in the secretion of intracellular succinate. Interaction assays demonstrate that the chemical inhibition of SDH activity potentiates the activity of other bioenergetic inhibitors and prevents the emergence of resistance to a variety of drugs. Overall, this study shows that SDH inhibitors are promising next-generation antimicrobials against M. tuberculosis.