Biology subjects

Dogovski, C.

Publications and source records attributed to Dogovski, C..

3 recordsLinked to original sources

bioRxiv2026

Potent reaction hijacking inhibitors of Plasmodium falciparum asparagine tRNA synthetase

Malaria remains one of the major threats to human health. Breakthrough drugs with high potency and low resistance risk are needed to combat the ever-increasing resistance to currently deployed antimalarials. Here, we explore a series of 4-amino-quinazoline-based sulfonamides, with drug-like physicochemical parameters and a synthetically accessible scaffold. Exemplars exhibit nanomolar potency against blood stage Plasmodium cultures, with up to 300-fold selectivity compared with a mammalian cell line. The compounds are also active against transmissible stages of P. falciparum and are refractory to resistance development. Targeted mass spectrometry reveals that the compounds act as reaction hijacking inhibitors targeting P. falciparum aminoacyl tRNA synthetases (aaRSs). Subtle changes to the chemical structure switch the main target from cytoplasmic tRNA threonine synthetase (PfThrRS) to cytoplasmic asparagine synthetase (PfAsnRS), a change that is associated with increased potency and selectivity. The target preference was confirmed by selective knock-down of different P. falciparum aaRSs and by tolerance selection in a mutator line. Consistent with aaRS targets, exemplar compounds activate the amino acid starvation response. Recombinant enzyme inhibition and thermal stabilisation assays confirm the susceptibility of PfAsnRS to reaction hijacking and show that human AsnRS is less susceptible. A molecular model of Asn-tRNA-bound PfAsnRS reveals that a potent hijacker adopts a pose similar to adenosine 5-monophosphate (AMP). An AlphaFold model of the native PfAsnRS dimer helps explain the tolerance-conferring effect of a mutation at the dimer interface.

biochemistry↗

bioRxiv2025

Natural product-mediated reaction hijacking mechanism validates Plasmodium aspartyl-tRNA synthetase as an antimalarial drug target

Malaria poses an enormous threat to human health. With ever-increasing resistance to currently deployed antimalarials, new targets and starting point compounds with novel mechanisms of action need to be identified. Here, we explore the antimalarial activity of the Streptomyces sp natural product, 5'-O-sulfamoyl-2-chloroadenosine (dealanylascamycin, DACM) and compare it with the synthetic adenosine monophosphate (AMP) mimic, 5-O-sulfamoyladenosine (AMS). These nucleoside sulfamates exhibit potent inhibition of P. falciparum growth with an efficacy comparable to that of the current front-line antimalarial dihydroartemisinin. Exposure of P. falciparum to DACM leads to inhibition of protein translation, driven by eIF2 phosphorylation. We show that DACM targets multiple amino acyl tRNA synthetase (aaRS) targets, including the cytoplasmic aspartyl tRNA synthetase (AspRS). The mechanism involves hijacking of the reaction product, leading to the formation of a tightly bound inhibitory amino acid-sulfamate conjugate. We show that recombinant P. falciparum and P. vivax AspRS are susceptible to hijacking by DACM and AMS, generating Asp-DACM and Asp-AMS adducts that stabilize these proteins. By contrast, human AspRS appears less susceptible to hijacking. X-ray crystallography reveals that apo P. vivax AspRS exhibits a stabilized flipping loop over the active site that is poised to bind substrates. By contrast, human AspRS exhibits disorder in an extended region around the flexible flipping loop as well as in a loop in motif II. These structural differences may underpin the decreased susceptibility of human AspRS to reaction-hijacking by DACM and AMS. Our work reveals Plasmodium AspRS as a promising antimalarial target and highlights structural features that underpin differences in the susceptibility of aaRSs to reaction hijacking inhibition.

biochemistry↗

bioRxiv2024

A potent and selective reaction hijacking inhibitor of Plasmodium falciparum tyrosine tRNA synthetase exhibits single dose oral efficacy in vivo

The Plasmodium falciparum cytoplasmic tyrosine tRNA synthetase (PfTyrRS) is an attractive drug target that is susceptible to reaction-hijacking by AMP-mimicking nucleoside sulfamates. We previously identified an exemplar pyrazolopyrimidine ribose sulfamate, ML901, as a potent pro-inhibitor of PfTyrRS. Here we examined the stage specificity of action of ML901, showing very good activity against the schizont stage, but lower trophozoite stage activity. We explored a series of ML901 analogues and identified ML471, which exhibits improved potency against trophozoites and enhanced selectivity against a human cell line. Additionally, it has no inhibitory activity against human ubiquitin-activating enzyme (UAE) in vitro. ML471 exhibits low nanomolar activity against asexual blood stage P. falciparum and potent activity against liver stage parasites, gametocytes and transmissible gametes. It is fast-acting and exhibits a long in vivo half-life. ML471 is well-tolerated and shows single dose oral efficacy in the SCID mouse model of P. falciparum malaria. We confirm that ML471 is a pro-inhibitor that is converted into a tight binding Tyr-ML471 conjugate by the PfTyrRS enzyme. A crystal structure of the PfTyrRS/ Tyr-ML471 complex offers insights into improved potency, while molecular docking into UAE provides a rationale for improved selectivity.

biochemistry↗