Overlooked Potential of EPSP Synthase as an Antimicrobial Target

Matthew Donghoon Han, Tayler Young, Godwin Chan, Kirill Pankov, Ruilin Wu, Mohammed Adam


The rise of antibiotic resistance has necessitated a need to discover novel drug candidates. We targeted an enzymatic protein found in Escherichia coli (E. coli) bacteria called 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS). EPSPS is an enzyme found in the shikimate pathway that forms EPSP and is essential for the downstream synthesis of vital aromatic amino acids: tryptophan, tyrosine, and phenylalanine. Using high-throughput (HTS) screening, we targeted a library of 1000+ compounds against the target of interest to discover inhibitors that significantly limited cellular growth. M9 minimal media was used in HTS to render EPSPS essential for bacteria. This media does not contain the aromatic amino acids, which would otherwise make EPSPS unnecessary for survival. Thus, we rationalized that minimal media had to be used to avoid cell survival from external sources of amino acids. After conducting HTS and normalizing the data, 8 successful inhibitors of the enzyme were identified. However, these findings cannot tell us whether or not the compounds were targeting EPSPS or inhibiting cellular growth via another mechanism. Therefore, a series of secondary screens have been proposed to hone in the target specificity of these 8 hits towards the shikimate pathway, EPSPS, and shikimate-3-phosphate binding site, in the given order. 

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