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Abstract Proliferating cell nuclear antigen (PCNA) is a homo‐trimeric protein complex that clamps around DNA to tether DNA polymerases to the template during replication and serves as a hub for many other interacting proteins. It regulates DNA metabolic processes and other vital cellar functions through the binding of proteins having short linear motifs (SLiMs) like the PIP‐box (PCNA‐interacting protein‐box) or the APIM (AlkB homolog 2 PCNA‐interacting motif) in the hydrophobic pocket where SLiMs bind. However, overproducing TbPCNA or human PCNA (hPCNA) in the pathogenic protistTrypanosoma bruceitriggers a dominant‐negative phenotype of arrested proliferation. The mechanism for arrestingT. bruceiproliferation requires the overproduced PCNA orthologs to have functional intact SLiM‐binding pocket. Sight‐directed mutagenesis studies showed thatT. bruceioverproducing PCNA variants with disrupted SLiM‐binding pockets grew normally. We hypothesized that chemically disrupting the SLiM‐binding pocket would restore proliferation inT. brucei, overproducing PCNA orthologs. Testing this hypothesis is the proof‐of‐concept for aT. brucei‐based PCNA screening assay. The assay design is to discover bioactive small molecules that restore proliferation inT. bruceistrains that overproduce PCNA orthologs, likely by disrupting interactions in the SLiM‐binding pocket. The pilot screen for this assay discovered two hit compounds that linked to predetermined PCNA targets. Compound#1, a known hPCNA inhibitor, had selective bioactivity to hPCNA overproduced inT. brucei, validating the assay. Compound#6had promiscuous bioactivity for hPCNA and TbPCNA but is the first compound discovered with bioactivity for inhibiting TbPCNA.
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Use of neomycin as a structured amino‐containing side chain motif for phenanthroline‐based G‐quadruplex ligands and telomerase inhibitors
Abstract In this paper, we report the synthesis of a phenanthroline and neomycin conjugate (7). Compound7binds to a human telomeric G‐quadruplex (G1) with a higher affinity compared with its parent compounds (phenanthroline and neomycin), which is determined by several biophysical studies. Compound7shows good selectivity for G‐quadruplex (G4) DNA over duplex DNA. The binding of7withG1is predominantly enthalpy‐driven, and the binding stoichiometry of7withG1is one for the tight‐binding event as determined by ESI mass spectrometry. A plausible binding mode is a synergistic effect of end‐stacking and groove interactions, as indicated by docking studies. Compound7can inhibit human telomerase activity at low micromolar concentrations, which is more potent than previously reported 5‐substituted phenanthroline derivatives.
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- Award ID(s):
- 1828179
- PAR ID:
- 10456948
- Publisher / Repository:
- Wiley-Blackwell
- Date Published:
- Journal Name:
- Chemical Biology & Drug Design
- Volume:
- 96
- Issue:
- 5
- ISSN:
- 1747-0277
- Page Range / eLocation ID:
- p. 1292-1304
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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