course of drug therapy necessary to cure Mycobacterium tuberculosis (Mtb) infections, and the continuing development of multiply drug resistant (MDR) and extremely drug resistant (XDR) strains of Mtb emphasize the ongoing need for new classes of antimycobacterials. Genomics together with biological studies have provided a number of new antibacterial targets. However, features unique to this bacillus - such as its slow rate of growth, its multiple growth states (including latency), and its nearly impenetrable cell wall make drug development challenging. One recently identified pathway unique to mycobacteria and some related actinomycetes is that of mycothiol biosynthesis and mycothiol-mediated detoxification, and mycothiol biosynthesis has been shown to be essential for growth of Mtb. This project seeks to design or discover inhibitors of mycothiol biosynthesis and detoxification, and to evaluate such inhibitors against Mtb. In addition to the chemistry efforts, this project requires substantial efforts in protein production and assay development. Recent progress has included development of an M. smegmatis/E.coli shuttle vector for expression of the essential biosynthetic enzyme MshC and large scale production of MshC for future screening efforts and structural studies. Synthetic efforts included construction of a series of substrate-mimic mycothiol analogs built upon quinic acid-derived or cyclohexylthioglycoside scaffold. By coupling synthetic and commercially available acid chlorides that share structural features with several bromotyrosine-derived marine natural products to the cyclohexylthioglycoside, we were able to generate natural product-substrate mimics that inhibit the enzymes MshB and MCA, and the growth of mycobacteria, with low micromolar IC50 values.
