The Q_i Site of Cytochrome b is a Promiscuous Drug Target in Trypanosoma cruzi and Leishmania donovani

Abstract

Available treatments for Chagas' disease and visceral leishmaniasis are inadequate, and there is a pressing need for new therapeutics. Drug discovery efforts for both diseases principally rely upon phenotypic screening. However, the optimization of phenotypically active compounds is hindered by a lack of information regarding their molecular target(s). To combat this issue we initiate target deconvolution studies at an early stage. Here, we describe comprehensive genetic and biochemical studies to determine the targets of three unrelated phenotypically active compounds. All three structurally diverse compounds target the Q i active-site of cytochrome b, part of the cytochrome bc1 complex of the electron transport chain. Our studies go on to identify the Q i site as a promiscuous drug target in Leishmania donovani and Trypanosoma cruzi with a propensity to rapidly mutate. Strategies to rapidly identify compounds acting via this mechanism are discussed to ensure that drug discovery portfolios are not overwhelmed with inhibitors of a single target.

Multiple unbiased approaches identify oxidosqualene cyclase as the molecular target of a promising anti-leishmanial

“…Genomic DNA was isolated from WT and resistant clones using a standard alkaline lysis protocol. Whole genomic sequencing was performed using a HiSeq4000 next-generation sequencing platform (Beijing Genomics Institute, Hong Kong) and the resulting data was analysed as described previously ( Wall et al., 2020 ), except the newly released LdBPKLV9 genome was also used as a reference. All associated datasets have been deposited with the European Nucleotide Archive under the following accession number: PRJEB37435.…”

“…For instance, compounds that act via mechanisms previously confirmed as unsuitable for drug development can be efficiently de-prioritized ( Riley et al., 2015 ; Wall et al., 2018 ). Compound series found to inhibit the same molecular target(s) can be prioritized and rationalized, thus mitigating against the overpopulation of pipelines with compounds acting via the same mechanism ( Wall et al., 2020 ). Furthermore, knowledge of the target pathway can be of potential value in optimizing drug combination therapy.…”

Rate-of-Kill (RoK) assays to triage large compound sets for Chagas disease drug discovery: Application to GSK Chagas Box

“…• The compound TCMDC-143087 is a known inhibitor of the Qi active site of cytochrome b, part of the cytochrome bc1 complex of the electron transport chain (ETC) [39]. It is active versus trypomastigotes at 48 and 72 hours with the same potency and have a cidal profile with low values of tlag and positive value of ME from 24 hours.…”

Chagas Disease Drug Discovery in Latin America—A Mini Review of Antiparasitic Agents Explored Between 2010 and 2021

“…Many orthogonal assays, as well as a broad range of expertise, are required (Wyatt et al, 2011;Field et al, 2017). In spite of the complexity of the process and inherent difficulties of genetically handling the parasite (Terstappen et al, 2007;Altamura et al, 2020), recent examples of successful target deconvolution efforts for CD include cytochrome b (Khare et al, 2015;Wall et al, 2020) and the proteasome (Khare et al, 2016). In this review, none of the publications reported the use of wide target deconvolution techniques, although some groups reported efforts to identify the mechanism of action of compounds using assays that monitor free radicals, mitochondria, or cell morphology.…”