RT Journal Article SR Electronic T1 Toward Broad Spectrum DHFR inhibitors Targeting Trimethoprim Resistant Enzymes Identified in Clinical Isolates of Methicillin-Resistant Staphylococcus aureus JF bioRxiv FD Cold Spring Harbor Laboratory SP 648808 DO 10.1101/648808 A1 Stephanie M. Reeve A1 Debjani Si A1 Jolanta Krucinska A1 Yongzhao Yan A1 Kishore Viswanathan A1 Siyu Wang A1 Graham T. Holt A1 Marcel S. Frenkel A1 Adegoke A. Ojewole A1 Alexavier Estrada A1 Sherry S. Agabiti A1 Jeremy B. Alverson A1 Nathan D. Gibson A1 Nigel D. Priestly A1 Andrew J. Wiemer A1 Bruce R. Donald A1 Dennis L. Wright YR 2019 UL http://biorxiv.org/content/early/2019/05/24/648808.abstract AB The spread of plasmid borne resistance enzymes in clinical Staphylococcus aureus isolates is rendering trimethoprim and iclaprim, both inhibitors of dihydrofolate reductase (DHFR), ineffective. Continued exploitation of these targets will require compounds that can broadly inhibit these resistance-confering isoforms. Using a structure-based approach, we have developed a novel class of ionized non-classical antifolates (INCAs) that capture the molecular interactions that have been exclusive to classical antifolates. These modifications allow for a greatly expanded spectrum of activity across these pathogenic DHFR isoforms, while maintaining the ability to penetrate the bacterial cell wall. Using biochemical, structural and computational methods, we are able to optimize these inhibitors to the conserved active sites of the endogenous and trimethoprim resistant DHFR enzymes. Here, we report a series of INCA compounds that exhibit low nanomolar enzymatic activity and potent cellular activity with human selectivity against a panel of clinically relevant TMPR MRSA isolates.IC50concentration for 50% inhibitory activityMICMinimum inhibitory concentrationsTMPRTrimethoprim resistantDHFRdihydrofolate reductase