Project description:We report here lead optimisation efforts of a new series of cytochrome bc1 oxidase inhibitors, the quinazoline derivatives. Four derivatives showed mild to no cytotoxicity as potent in vitro and ex vivo activity in infected THP-1 macrophages against M. tuberculosis. Isolation of resistant mutants to one of the derivatives in M. tuberculosis revealed mutations in both QcrA and QcrB of the cytochrome bc1 oxidase, one of two terminal oxidases of the mycobacterial electron transport chain. Cross-resistance studies, transcriptomic analyses and bioenergetics flux assays provide further evidence of the cytochrome bc1 as the target of the quinazolines compounds. The transcriptomic and bioenergetic profiles obtained when M. tuberculosis was treated with 11626252 are similar to transcriptomic and respiratory signatures of other cytochrome bc1 oxidase inhibitors.
Project description:The increasing incidence of antimalarial drug resistance to the first-line artemisinins, and their combination partner drugs, underpins an urgent need for new antimalarial drugs, ideally with a novel mechanism of action. The recently developed 2-aminomethylphenol, JPC-3210, (MMV 892646) is an erythrocytic schizonticide with potent in vitro antimalarial activity against multidrug-resistant Plasmodium falciparum, low cytotoxicity, potent in vivo efficacy against murine malaria, and favourable preclinical pharmacokinetics, including a lengthy plasma elimination half-life. This study demonstrates the application of a “multi-omics” workflow based on high resolution orbitrap mass spectrometry to investigate the impact of JPC-3210 on biochemical pathways within P. falciparum infected red blood cells. Metabolomics and peptidomics analysis revealed a perturbation in hemoglobin metabolism following JPC-3210 exposure. The metabolomics data demonstrated a depletion in short hemoglobin-derived peptides, while peptidomics analysis showed a depletion in longer hemoglobin-derived peptides. In order to further elucidate the mechanism responsible for inhibition of hemoglobin metabolism, we used in vitro β-hematin polymerisation assays and showed JPC-3210 to be an intermediate inhibitor of β-hematin polymerisation, about 10-fold less potent then the quinoline antimalarials. Furthermore, quantitative proteomics analysis showed that JPC-3210 treatment results in a distinct proteomic signature in comparison to other known antimalarials. Whilst JPC-3210 clustered closely with mefloquine in the metabolomics and proteomics analyses, a key differentiating signature for JPC-3210 was the significant enrichment of parasite proteins involved in regulation of translation. In conclusion, multi-omics studies using high resolution mass spectrometry revealed JPC-3210 to possess a unique mechanism of action involving inhibition of hemoglobin digestion, depletion of DNA replication and synthesis proteins, and elevation of regulators of protein translation. Importantly, this mechanism is distinct from currently-used antimalarials, suggesting that JPC-3210 warrants further investigation as a potentially useful new antimalarial agent.
Project description:Candida auris has emerged as a problematic fungal pathogen associated with high morbidity and mortality. Amphotericin B (AmB) is the most effective antifungal used to treat invasive fungal candidiasis, with resistance rarely observed among clinical isolates. However, C. auris possesses extraordinary resistant profiles against all available antifungal drugs, including AmB. In our pursuit of potential solutions, we conducted a screening of a panel of 727 FDA-approved drugs and identified the proton pump inhibitor lansoprazole (LNP) as a potent enhancer of AmB’s activity against C. auris. LNP also potentiates the antifungal activity of AmB against other medically important species of Candida and Cryptococcus. Our investigations into the mechanism of action unveiled that LNP metabolite(s) interact with a crucial target in the mitochondrial respiratory chain (complex III, known as cytochrome bc1). This interaction increases oxidative stress within fungal cells. Our results demonstrated the critical role of an active respiratory function in the antifungal activity of LNP. Most importantly, LNP restored the efficacy of AmB in an immunocompromised mouse model, resulting in a 1.7-log (~98%) CFU reduction in the burden of C. auris in the kidneys. Our findings strongly advocate for a thorough and comprehensive evaluation of LNP as a cytochrome bc1 inhibitor for combating drug-resistant C. auris infections.
Project description:We report here lead optimisation efforts for molecule GW861072X, one of 177 leads published in a GSK-led phenotypic screening campaign by Balell et al. (2013), generating the AX series. Along with the parent compound AX-35, four other derivatives with mild to no cytotoxicity showed potent in vitro and ex vivo activity in infected THP-1 macrophages against M. tuberculosis. Isolation of resistant mutants to AX compounds in M. tuberculosis revealed mutations in the QcrB of the cytochrome bc1 oxidase, one of two terminal oxidases of the mycobacterial electron transport chain. Cross-resistance studies, transcriptomic analyses and bioenergetics flux assays provide further evidence of QcrB as the target of the AX compounds, and that AX compounds likely interact differently with the quinol binding pocket compared to other QcrB inhibitors. The transcriptomic and bioenergetic profiles obtained when M. tuberculosis was treated with AX-35 are similar to transcriptomic and respiratory signatures of other cytochrome bc1 oxidase inhibitors, whereby the pronounced role of the alternate terminal oxidase cytochrome bd in the respiratory adaptation of M. tuberculosis could be observed. Genes involved in utilisation and synthesis of triacylglycerol (TAG) were also additionally observed to be up-regulated with AX treatment, indicating a switch induced towards lipid metabolism under this particular stress.
Project description:The increasing incidence of antimalarial drug resistance to the first-line artemisinins, and their combination partner drugs, underpins an urgent need for new antimalarial drugs, ideally with a novel mechanism of action. The recently developed 2-aminomethylphenol, JPC-3210, (MMV 892646) is an erythrocytic schizonticide with potent in vitro antimalarial activity against multidrug-resistant Plasmodium falciparum, low cytotoxicity, potent in vivo efficacy against murine malaria, and favourable preclinical pharmacokinetics, including a lengthy plasma elimination half-life. This study demonstrates the application of a “multi-omics” workflow based on high resolution orbitrap mass spectrometry to investigate the impact of JPC-3210 on biochemical pathways within P. falciparum infected red blood cells. Metabolomics and peptidomics analysis revealed a perturbation in hemoglobin metabolism following JPC-3210 exposure. The metabolomics data demonstrated a depletion in short hemoglobin-derived peptides, while peptidomics analysis showed a depletion in longer hemoglobin-derived peptides. In order to further elucidate the mechanism responsible for inhibition of hemoglobin metabolism, we used in vitro β-hematin polymerisation assays and showed JPC-3210 to be an intermediate inhibitor of β-hematin polymerisation, about 10-fold less potent then the quinoline antimalarials. Furthermore, quantitative proteomics analysis showed that JPC-3210 treatment results in a distinct proteomic signature in comparison to other known antimalarials. Whilst JPC-3210 clustered closely with mefloquine in the metabolomics and proteomics analyses, a key differentiating signature for JPC-3210 was the significant enrichment of parasite proteins involved in regulation of translation. In conclusion, multi-omics studies using high resolution mass spectrometry revealed JPC-3210 to possess a unique mechanism of action involving inhibition of hemoglobin digestion, depletion of DNA replication and synthesis proteins, and elevation of regulators of protein translation. Importantly, this mechanism is distinct from currently-used antimalarials, suggesting that JPC-3210 warrants further investigation as a potentially useful new antimalarial agent.
Project description:Plasmodium parasites are reliant on the Apicomplexan AP2 (ApiAP2) transcription factor family to regulate gene expression programs. AP2 DNA binding domains have no homologs in the human or mosquito host genomes, making them potential antimalarial drug targets. Using an in-silico screen to dock thousands of small molecules into the crystal structure of the AP2-EXP (Pf3D7_1466400) AP2 domain (PDB:3IGM), we identified compounds that interact with this domain. Four compounds were found to compete for DNA binding with AP2-EXP and at least one additional ApiAP2 protein. Our top ApiAP2 competitor compound perturbs the transcriptome of P. falciparum trophozoites and results in a decrease in abundance of log2 fold change > 2 for 50% (46/93) of AP2-EXP target genes. Additionally, two ApiAP2 competitor compounds have multi-stage anti-Plasmodium activity against blood and mosquito stage parasites. In summary, we describe a novel set of antimalarial compounds that are targeted against the ApiAP2 family of proteins. These compounds may be used for future chemical genetic interrogation of ApiAP2 proteins or serve as starting points for a new class of antimalarial therapeutics.
Project description:Bacteria modify expression of different types of terminal oxidase in response to oxygen availability. Corynebacterium glutamicum, a facultative anaerobic bacterium in Actinobacteria, possesses aa3-type cytochrome c oxidase and cytochrome bd-type quinol oxidase, the latter of which is induced upon oxygen limitation. We report here that an extracytoplasmic function sigma factor, SigC, is unprecedentedly responsible for the regulation. Chromatin immunoprecipitation in conjunction with microarray (ChIP-chip) analysis detected eight SigC-binding regions in the genome, leading to identification of a consensus promoter sequence for SigC recognition. The promoter sequences were found upstream of genes for cytochrome bd, heme a synthesis enzymes, and uncharacterized membrane proteins, all of which were upregulated by sigC overexpression. In contrast, that found on the antisense strand upstream of an operon encoding the cytochrome bc1 complex conferred a SigC-dependent negative effect on the operon expression. The SigC regulon was induced by cytochrome aa3 deficiency without modification of expression of sigC itself, but not by deficiency of the bc1 complex. These findings suggest that SigC is activated in response to impairment of electron transfer via cytochrome aa3, not directly to shift in oxygen levels. Our results provide a novel paradigm for transcriptional regulation of the aerobic respiratory system in bacteria. Comparison of gene expression profiles of the wild type before and after sigC overexpression at the exponential phase. Three independent experiments were performed.
Project description:Bacteria modify expression of different types of terminal oxidase in response to oxygen availability. Corynebacterium glutamicum, a facultative anaerobic bacterium in Actinobacteria, possesses aa3-type cytochrome c oxidase and cytochrome bd-type quinol oxidase, the latter of which is induced upon oxygen limitation. We report here that an extracytoplasmic function sigma factor, SigC, is unprecedentedly responsible for the regulation. Chromatin immunoprecipitation in conjunction with microarray (ChIP-chip) analysis detected eight SigC-binding regions in the genome, leading to identification of a consensus promoter sequence for SigC recognition. The promoter sequences were found upstream of genes for cytochrome bd, heme a synthesis enzymes, and uncharacterized membrane proteins, all of which were upregulated by sigC overexpression. In contrast, that found on the antisense strand upstream of an operon encoding the cytochrome bc1 complex conferred a SigC-dependent negative effect on the operon expression. The SigC regulon was induced by cytochrome aa3 deficiency without modification of expression of sigC itself, but not by deficiency of the bc1 complex. These findings suggest that SigC is activated in response to impairment of electron transfer via cytochrome aa3, not directly to shift in oxygen levels. Our results provide a novel paradigm for transcriptional regulation of the aerobic respiratory system in bacteria.
Project description:Bacteria modify expression of different types of terminal oxidase in response to oxygen availability. Corynebacterium glutamicum, a facultative anaerobic bacterium in Actinobacteria, possesses aa3-type cytochrome c oxidase and cytochrome bd-type quinol oxidase, the latter of which is induced upon oxygen limitation. We report here that an extracytoplasmic function sigma factor, SigC, is unprecedentedly responsible for the regulation. Chromatin immunoprecipitation in conjunction with microarray (ChIP-chip) analysis detected eight SigC-binding regions in the genome, leading to identification of a consensus promoter sequence for SigC recognition. The promoter sequences were found upstream of genes for cytochrome bd, heme a synthesis enzymes, and uncharacterized membrane proteins, all of which were upregulated by sigC overexpression. In contrast, that found on the antisense strand upstream of an operon encoding the cytochrome bc1 complex conferred a SigC-dependent negative effect on the operon expression. The SigC regulon was induced by cytochrome aa3 deficiency without modification of expression of sigC itself, but not by deficiency of the bc1 complex. These findings suggest that SigC is activated in response to impairment of electron transfer via cytochrome aa3, not directly to shift in oxygen levels. Our results provide a novel paradigm for transcriptional regulation of the aerobic respiratory system in bacteria.