Specific anti-TB compounds from uncultured bacteria

DESCRIPTION provided by applicant The slow pace of antibiotic discovery is being outmatched by rapid acquisition of resistance by our pathogens The need is especially acute in the case of Mycobacterium tuberculosis TB where strains of XDR TB resistant to the majority of standard therapeutics are rapidly spreading In a previous RO screen development project we collaborated with Professor Kim Lewis Northeastern University to establish a drug discovery platform for identifying compounds specifically acting against TB The platform is based on two innovations the use of uncultured bacteria as an untapped source of secondary metabolites and a species specific screen Uncultured bacteria represent of all species and we access them by cultivation in their natural environment the soil in a specialized diffusion chamber Our findings show that this is an excellent source of novel antimicrobials However even with this previously inaccessible resource most of the effort is wasted on rediscovering known compounds We reasoned that the background can be eliminated if discovery is focused on a species specific compound Natural compounds specifically acting against TB are essentially unknown so a screen for specific anti TB compounds will produce hits that will have a high probability of being novel substances A TB specific compound will likely not hit a target present in humans and will not harm the human microbiome We performed a pilot screen against TB and a counter screen against Staphylococcus aureus The screen produced a hit rate of for TB specific extracts One of the extracts from a rare Actinomycete contained a novel antimicrobial with excellent activity against TB high specificity for mycobacteria and no cytotoxicity This compound which we named lassomycin killed both growing and dormant cells of TB better than the best current killing agent rifampicin Whole genome sequencing of lassomycin resistant mutants showed that it targets the C subunit of the essential mycobacterial ClpP P C Lassomycin inhibits this protease and activates the ATPase of ClpC This dual action is responsible for the excellent killing Lassomycin serves as proof of principle for this platform In the proposed project the PI Losee Ling VP of Biology at NovoBiotic will continue collaborating with Dr Kim Lewis to perform a large scale screen of extracts from uncultured bacteria for TB specific compounds The compounds will be isolated structurally characterized and tested against a panel of gut symbionts to establish novelty and specificity The principal mode of action will be identified by whole genome sequencing of resistant mutants The result of the project will be eight validated leads providing a solid basis for a subsequent Phase II effort aimed at drug development PUBLIC HEALTH RELEVANCE Tuberculosis remains a leading health crisis with one third of the worldandapos s population infected and antibiotic resistance a growing problem Discovery of novel compounds acting specifically against Mycobacterium tuberculosis will enable the development of new anti TB therapies