Mycobacterium tuberculosis (Mtb) is the causative agent of the disease Tuberculosis (TB), and it employs the type II fatty acid synthase (FAS-II) metabolic pathway. Mtb FAS-II is responsible for producing very long chain fatty acids (VLCFA) which are the precursors for mycolic acids and crucial structural components of the mycobacterial cell wall. These unique structural components decrease cell wall permeability and limit the efficacy of current treatments. The occurrence of multidrug resistant (MDR) and extensively drug resistant (XDR) TB infections have continued to rise, especially in underdeveloped countries where resources are limited, escalating the need for new, and more sustainable treatments that target essential pathways like FAS-II. To study the regulatory protein-protein interactions in FAS-II, our lab has developed methods that use mechanistic crosslinking of the transient acyl carrier protein (ACP) with its partner proteins in E. coli. This work highlights the extended applications of these methods to the Mtb FAS-II system where we investigate the protein-protein interactions between Mtb ACP (AcpM) and one of its dehydratases (DH), HadAB. Results demonstrate that a fluorescently labeled probe previously used to crosslink E. coli FAS-II proteins is successful in labeling HadAB, confirming that the methods developed for studying the E. coli system have translational potential. We then tested a previously used substrate mimetic that is structurally similar to the fluorescent probe based on its successful use in crosslinking the E. coli DH and ACP. Here we show the results of the crosslinking experiments between AcpM and HadAB. Future work will incorporate computational tools and molecular dynamic simulations to further investigate the druggability and therapeutic potential of targeting these protein-protein interactions.

Sho Konno

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