Functional and structural characterization of the fatty acid synthase type I from Mycobacterium tuberculosis

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Fatty acid synthase type I (FAS I) systems are large multifunctional proteins which harbor several enzymatic activities on one polypeptide chain. FAS I proteins occur characteristically in the cytoplasm of eukaryotic cells. Recently, the X-ray structures of the FAS I complexes in fungi and in mammals were solved, and enabled deep insight into fatty acid synthesis and the general working mode of such multifunctional proteins. Bacterial fatty acid synthesis generally occurs in separated proteins (type II system); however, type I systems have been characterized in bacteria of e.g. genus Mycobacterium (order Actinomycetales). Mycobacterium tuberculosis FAS I has a bimodal product spectrum producing C16/C18 and C24/C26 fatty acids. The mycobacterial FAS I is a highly demanded target for rational drug design. The inhibition of this protein is part of the 6 months standard treatment regime of tuberculosis (TB), a human infectious disease which is usually caused by M. tuberculosis. The goal of this project is to establish a toolkit for functional and structural studies to the inhibition of the M. tuberculosis FAS I. We pursue an innovative approach, where we recombinantly express M. tuberculosis FAS I in Escherichia coli. Due to a native type II fatty acid metabolism, E. coli growth is virtually independent from recombinant FAS I production which allows unrestricted protein engineering and in vitro mutational analysis for guiding M. tuberculosis FAS I inhibitor design by structural and functional methods.