Coenzyme F420, helping mycobacteria find a niche in humans

Project summary Mycobacterium tuberculosis, the causative agent of TB, remains an important cause of morbidity and mortality worldwide. Persistence in hypoxic conditions within granuloma is the hallmark of TB, leading to latent infection and limiting the application of current therapies. Understanding how M. tuberculosis supports its metabolism under hypoxic conditions, and adapts to these challenges, is key to eliminating latent TB. “Disarming” M. tuberculosis by removing its ability to endure the stress-inducing conditions in granuloma will provide a feasible strategy for clinical interventions against latent TB. We will investigate the role of the coenzyme F420 in the physiology and pathogenesis of M. tuberculosis. F420 is a deazaflavin that acts as a carrier in a wide range of hydride transfer reactions. Growing evidence points to the wide use of this cofactor by M. tuberculosis, with its low redox potential thought to give it key roles in hypoxic persistence. There appears to be F420-dependent mechanisms in mycobacteria that are used to protect against oxidative and nitrosative stress, but the contribution of F420 to M. tuberculosis metabolism and persistence remains unclear. The ultimate goal of the project is to investigate how F420 facilitates M. tuberculosis’ survival under hypoxic conditions within granuloma, elucidating its role in persistence. We have devised an integrated experimental approach using genetics, metabolomics, animal infection models, and protein biochemistry tools to determine how F420 helps M. tuberculosis persist during pathogenesis. We will construct a set of conditional knockdown strains targeting F420 biosynthesis and metabolism, and perform in vitro studies to determine how M. tuberculosis utilizes F420 under hypoxic conditions and during re-growth after hypoxia-induced dormancy. We will then perform infection studies in a mouse model that develops necrotic and hypoxic TB lesions to investigate how F420 facilitates M. tuberculosis survival inside granuloma and to understand the link between F420 and persistence. Finally, we will reveal structural insights into the biosynthesis of F420 chromophore, providing the foundations for mechanistic and inhibition studies of this essential reaction in F420 biosynthesis.