Inhibition ofPlasmodium falciparumLysyl-tRNA synthetase via an anaplastic lymphoma kinase inhibitor

Abstract

Aminoacyl-tRNA synthetases are attractive targets for the development of antibacterial, antifungal, antiparasitic agents and for the treatment of other human diseases. Lysyl-tRNA synthetase (LysRS) from this family has been validated as a promising target for the development of antimalarial drugs. Here, we developed a high-throughput compatible assay and screened 1215 bioactive compounds to identify Plasmodium falciparum cytoplasmic LysRS (PfLysRS) inhibitor. ASP3026, an anaplastic lymphoma kinase inhibitor that was used in clinical trials for the treatment of B-cell lymphoma and solid tumors, was identified as a novel PfLysRS inhibitor. ASP3026 suppresses the enzymatic activity of PfLysRS at nanomolar potency, which is >380-fold more effective than inhibition of the human counterpart. In addition, the compound suppressed blood-stage P. falciparum growth. To understand the molecular mechanism of inhibition by ASP3026, we further solved the cocrystal structure of PfLysRS-ASP3026 at a resolution of 2.49 Å, providing clues for further optimization of the compound. Finally, primary structure-activity relationship analyses indicated that the inhibition of PfLysRS by ASP3026 is highly structure specific. This work not only provides a new chemical scaffold with good druggability for antimalarial development but also highlights the potential for repurposing kinase-inhibiting drugs to tRNA synthetase inhibitors to treat human diseases.

Aminoacyl-tRNA Synthetases as Valuable Targets for Antimicrobial Drug Discovery

“…To identify a new scaffold for P. falciparum cytoplasmic LysRS (Pf-LysRS) inhibitors, Zhou et al screened 1215 bioactive agents from Selleck Chemicals using a high-throughput thermal shift assay [ 96 ]. Eighteen compounds were identified providing an increase in melting temperature (T m ) above 4 °C.…”

“…However, it has no synergistic activity in the presence of lysine nor does it interfere with the binding of the lysine substrate. The crystal structure shows that this compound occupies the ATP binding pocket with the triazine ring stacking with the class II conserved Phe342, the sulfonyl group located in the normal ribose site of ATP, and the methylpiperazine extending out of the pocket [ 96 ] ( Figure 6 ). The latter can potentially sterically clash with the 3′-terminus of tRNA according to modeling.…”

“…Thus, a number of halofuginone derivatives have been reported and a new lead compound (2′S,2R,3S)-halofuginol (Figure 5a) possesses 65-fold higher selectivity against P. falciparum ProRS over the human homolog while still preserving excellent potency (EC50 = 14 nM) in the in vitro P. berghei ANKA strain liver-stage model [95]. To identify a new scaffold for P. falciparum cytoplasmic LysRS (Pf-LysRS) inhibitors, Zhou et al screened 1215 bioactive agents from Selleck Chemicals using a high-throughput thermal shift assay [96]. Eighteen compounds were identified providing an increase in melting temperature (T m ) above 4 • C. Among them, ASP3026 (Figure 6), a known anaplastic lymphoma kinase inhibitor that has already been evaluated for the treatment of B-cell lymphoma and solid tumors in clinical trials, was shown to be a potent novel Pf-LysRS inhibitor [96].…”

“…To identify a new scaffold for P. falciparum cytoplasmic LysRS (Pf-LysRS) inhibitors, Zhou et al screened 1215 bioactive agents from Selleck Chemicals using a high-throughput thermal shift assay [96]. Eighteen compounds were identified providing an increase in melting temperature (T m ) above 4 • C. Among them, ASP3026 (Figure 6), a known anaplastic lymphoma kinase inhibitor that has already been evaluated for the treatment of B-cell lymphoma and solid tumors in clinical trials, was shown to be a potent novel Pf-LysRS inhibitor [96]. An ATP hydrolysis assay showed that this compound suppresses Pf-LysRS enzymatic activity with an IC 50 value of 657 nM, which is over 380-fold more selective than for the human ortholog (IC 50 > 250 µM).…”

“…in melting temperature (Tm) above 4 °C. Among them, ASP3026 (Figure 6), a known anaplastic lymphoma kinase inhibitor that has already been evaluated for the treatment of Bcell lymphoma and solid tumors in clinical trials, was shown to be a potent novel Pf-LysRS inhibitor [96]. An ATP hydrolysis assay showed that this compound suppresses Pf-LysRS enzymatic activity with an IC50 value of 657 nM, which is over 380-fold more selective than for the human ortholog (IC50 > 250 µM).…”