Identification of inhibitors of an unconventional Trypanosoma brucei kinetochore kinase

Leah Torrie, Fabio Zuccotto, David Robinson, David Gray, Ian Gilbert (Lead / Corresponding author), Manu De Rycker (Lead / Corresponding author)

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Abstract

The discovery of 20 unconventional kinetochore proteins in Trypanosoma brucei has opened a new and interesting area of evolutionary research to study a biological process previously thought to be highly conserved in all eukaryotes. In addition, the discovery of novel proteins involved in a critical cellular process provides an opportunity to exploit differences between kinetoplastid and human kinetochore proteins to develop therapeutics for diseases caused by kinetoplastid parasites. Consequently, we identified two of the unconventional kinetochore proteins as key targets (the highly related kinases KKT10 and KKT19). Recombinant T. brucei KKT19 (TbKKT19) protein was produced, a peptide substrate phosphorylated by TbKKT19 identified (KKLRRTLSVA), Michaelis constants for KKLRRTLSVA and ATP were determined (179 μM and 102 μM respectively) and a robust high-throughput compatible biochemical assay developed. This biochemical assay was validated pharmacologically with inhibition by staurosporine and hypothemycin (IC50 values of 288 nM and 65 nM respectively). Surprisingly, a subsequent high-throughput screen of a kinase-relevant compound library (6,624 compounds) yielded few hits (8 hits; final hit rate 0.12%). The low hit rate observed was unusual for a kinase target, particularly when screened against a compound library enriched with kinase hinge binding scaffolds. In an attempt to understand the low hit rate a TbKKT19 homology model, based on human cdc2-like kinase 1 (CLK1), was generated. Analysis of the TbKKT19 sequence and structure revealed no obvious features that could explain the low hit rates. Further work will therefore be necessary to explore this unique kinetochore kinase as well as to assess whether the few hits identified can be developed into tool molecules or new drugs.
Original languageEnglish
Article numbere0217828
Pages (from-to)1-16
Number of pages16
JournalPLoS ONE
Volume14
Issue number5
DOIs
Publication statusPublished - 31 May 2019

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Kinetochores
Trypanosoma brucei
kinetochores
Trypanosoma brucei brucei
phosphotransferases (kinases)
Phosphotransferases
Proteins
proteins
Libraries
Assays
Throughput
Biological Phenomena
Staurosporine
new drugs
assays
Hinges
Eukaryota
Scaffolds
Inhibitory Concentration 50
inhibitory concentration 50

Cite this

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title = "Identification of inhibitors of an unconventional Trypanosoma brucei kinetochore kinase",
abstract = "The discovery of 20 unconventional kinetochore proteins in Trypanosoma brucei has opened a new and interesting area of evolutionary research to study a biological process previously thought to be highly conserved in all eukaryotes. In addition, the discovery of novel proteins involved in a critical cellular process provides an opportunity to exploit differences between kinetoplastid and human kinetochore proteins to develop therapeutics for diseases caused by kinetoplastid parasites. Consequently, we identified two of the unconventional kinetochore proteins as key targets (the highly related kinases KKT10 and KKT19). Recombinant T. brucei KKT19 (TbKKT19) protein was produced, a peptide substrate phosphorylated by TbKKT19 identified (KKLRRTLSVA), Michaelis constants for KKLRRTLSVA and ATP were determined (179 μM and 102 μM respectively) and a robust high-throughput compatible biochemical assay developed. This biochemical assay was validated pharmacologically with inhibition by staurosporine and hypothemycin (IC50 values of 288 nM and 65 nM respectively). Surprisingly, a subsequent high-throughput screen of a kinase-relevant compound library (6,624 compounds) yielded few hits (8 hits; final hit rate 0.12{\%}). The low hit rate observed was unusual for a kinase target, particularly when screened against a compound library enriched with kinase hinge binding scaffolds. In an attempt to understand the low hit rate a TbKKT19 homology model, based on human cdc2-like kinase 1 (CLK1), was generated. Analysis of the TbKKT19 sequence and structure revealed no obvious features that could explain the low hit rates. Further work will therefore be necessary to explore this unique kinetochore kinase as well as to assess whether the few hits identified can be developed into tool molecules or new drugs.",
author = "Leah Torrie and Fabio Zuccotto and David Robinson and David Gray and Ian Gilbert and {De Rycker}, Manu",
note = "We also acknowledge the support of the Protein Production, Compound Management and Data Management Teams within the Wellcome Centre for Anti-Infectives Research (WCAIR). This work was funded by Wellcome Trust (https://wellcome.ac.uk/) awards 092340 and 204672.",
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T1 - Identification of inhibitors of an unconventional Trypanosoma brucei kinetochore kinase

AU - Torrie, Leah

AU - Zuccotto, Fabio

AU - Robinson, David

AU - Gray, David

AU - Gilbert, Ian

AU - De Rycker, Manu

N1 - We also acknowledge the support of the Protein Production, Compound Management and Data Management Teams within the Wellcome Centre for Anti-Infectives Research (WCAIR). This work was funded by Wellcome Trust (https://wellcome.ac.uk/) awards 092340 and 204672.

PY - 2019/5/31

Y1 - 2019/5/31

N2 - The discovery of 20 unconventional kinetochore proteins in Trypanosoma brucei has opened a new and interesting area of evolutionary research to study a biological process previously thought to be highly conserved in all eukaryotes. In addition, the discovery of novel proteins involved in a critical cellular process provides an opportunity to exploit differences between kinetoplastid and human kinetochore proteins to develop therapeutics for diseases caused by kinetoplastid parasites. Consequently, we identified two of the unconventional kinetochore proteins as key targets (the highly related kinases KKT10 and KKT19). Recombinant T. brucei KKT19 (TbKKT19) protein was produced, a peptide substrate phosphorylated by TbKKT19 identified (KKLRRTLSVA), Michaelis constants for KKLRRTLSVA and ATP were determined (179 μM and 102 μM respectively) and a robust high-throughput compatible biochemical assay developed. This biochemical assay was validated pharmacologically with inhibition by staurosporine and hypothemycin (IC50 values of 288 nM and 65 nM respectively). Surprisingly, a subsequent high-throughput screen of a kinase-relevant compound library (6,624 compounds) yielded few hits (8 hits; final hit rate 0.12%). The low hit rate observed was unusual for a kinase target, particularly when screened against a compound library enriched with kinase hinge binding scaffolds. In an attempt to understand the low hit rate a TbKKT19 homology model, based on human cdc2-like kinase 1 (CLK1), was generated. Analysis of the TbKKT19 sequence and structure revealed no obvious features that could explain the low hit rates. Further work will therefore be necessary to explore this unique kinetochore kinase as well as to assess whether the few hits identified can be developed into tool molecules or new drugs.

AB - The discovery of 20 unconventional kinetochore proteins in Trypanosoma brucei has opened a new and interesting area of evolutionary research to study a biological process previously thought to be highly conserved in all eukaryotes. In addition, the discovery of novel proteins involved in a critical cellular process provides an opportunity to exploit differences between kinetoplastid and human kinetochore proteins to develop therapeutics for diseases caused by kinetoplastid parasites. Consequently, we identified two of the unconventional kinetochore proteins as key targets (the highly related kinases KKT10 and KKT19). Recombinant T. brucei KKT19 (TbKKT19) protein was produced, a peptide substrate phosphorylated by TbKKT19 identified (KKLRRTLSVA), Michaelis constants for KKLRRTLSVA and ATP were determined (179 μM and 102 μM respectively) and a robust high-throughput compatible biochemical assay developed. This biochemical assay was validated pharmacologically with inhibition by staurosporine and hypothemycin (IC50 values of 288 nM and 65 nM respectively). Surprisingly, a subsequent high-throughput screen of a kinase-relevant compound library (6,624 compounds) yielded few hits (8 hits; final hit rate 0.12%). The low hit rate observed was unusual for a kinase target, particularly when screened against a compound library enriched with kinase hinge binding scaffolds. In an attempt to understand the low hit rate a TbKKT19 homology model, based on human cdc2-like kinase 1 (CLK1), was generated. Analysis of the TbKKT19 sequence and structure revealed no obvious features that could explain the low hit rates. Further work will therefore be necessary to explore this unique kinetochore kinase as well as to assess whether the few hits identified can be developed into tool molecules or new drugs.

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