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Discovery and Characterization of the Antimetabolite Action of Thioacetamide-Linked 1,2,3-Triazoles as Disruptors of Cysteine Biosynthesis in Gram-Negative Bacteria
journal contribution
posted on 2020-01-13, 17:38 authored by Miranda
J. Wallace, Suresh Dharuman, Dinesh M. Fernando, Stephanie M. Reeve, Clifford T. Gee, Jiangwei Yao, Elizabeth C. Griffith, Gregory A. Phelps, William C. Wright, John M. Elmore, Robin B. Lee, Taosheng Chen, Richard E. LeeIncreasing
rates of drug-resistant Gram-negative (GN) infections,
combined with a lack of new GN-effective antibiotic classes, are driving
the need for the discovery of new agents. Bacterial metabolism represents
an underutilized mechanism of action in current antimicrobial therapies.
Therefore, we sought to identify novel antimetabolites that disrupt
key metabolic pathways and explore the specific impacts of these agents
on bacterial metabolism. This study describes the successful application
of this approach to discover a new series of chemical probes, N-(phenyl)thioacetamide-linked 1,2,3-triazoles (TAT), that
target cysteine synthase A (CysK), an enzyme unique to bacteria that
is positioned at a key juncture between several fundamental pathways.
The TAT class was identified using a high-throughput screen against Escherichia coli designed to identify modulators of pathways
related to folate biosynthesis. TAT analog synthesis demonstrated
a clear structure–activity relationship, and activity was confirmed
against GN antifolate-resistant clinical isolates. Spontaneous TAT
resistance mutations were tracked to CysK, and mode of action studies
led to the identification of a false product formation mechanism between
the CysK substrate O-acetyl-l-serine and
the TATs. Global transcriptional responses to TAT treatment revealed
that these antimetabolites impose substantial disruption of key metabolic
networks beyond cysteine biosynthesis. This study highlights the potential
of antimetabolite drug discovery as a promising approach to the discovery
of novel GN antibiotics and the pharmacological promise of TAT CysK
probes.
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Keywords
novel GN antibioticscysteine biosynthesisTAT CysK probesTAT classantimetabolite drug discoveryhigh-throughput screenproduct formation mechanismGram-Negative Bacteriatarget cysteine synthaseTAT treatmentGlobal transcriptional responsesGN antifolate-resistantAntimetabolite Actionnovel antimetabolitesCysK substrate Oantimicrobial therapieschemical probesEscherichia coliCysteine Biosynthesisfolate biosynthesisGN-effective antibiotic classesTAT analog synthesispathwaySpontaneous TAT resistance mutationsBacterial metabolismaction studies
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