Biology subjects

Goodman, C. D.

Publications and source records attributed to Goodman, C. D..

5 recordsLinked to original sources

bioRxiv2026

Mutations in apicoplast rRNA genes are associated with clindamycin resistance and impair the ability of malaria parasites to infect mosquitoes

Drug resistance hampers malaria treatment and control. Resistance to nearly all clinically used antimalarials has emerged and spread globally. With multi-drug-resistant parasites now on the rise, understanding resistance mechanisms, and their ability to spread, is crucial for optimal treatment and control strategies. Clindamycin is an apicoplast-targeting antimalarial used as a partner compound in second-line treatment combinations, but mechanisms of clindamycin resistance remain largely unexplored, and it is unclear whether resistant parasites could spread readily. We selected in vitro for clindamycin resistance in African and Southeast Asian strains of Plasmodium falciparum. All resistant lines carried mutations in the apicoplast-encoded large ribosomal subunit RNA (23S rRNA), reminiscent of clindamycin resistance mechanisms found in bacteria. We recovered three different mutations, all located in the peptidyl transferase region of apicoplast 23S rRNA. Each 23S rRNA mutation was associated with >20-fold resistance, although some mutants grew extremely poorly in vitro and therefore may lack clinical relevance in vivo. We assessed how well our most vigorously growing 23S rRNA mutant could infect Anopheles mosquitoes and found a modest reduction in vector infectivity, indicating that high-level clindamycin resistance is likely to be transmissible in the field. This is in contrast to atovaquone resistance, which exhibits a total block to transmission (and hence spread), and azithromycin resistance, which does not significantly impact P. falciparum development in the mosquito.

molecular biology↗

bioRxiv2023

Malaria parasite resistance to azithromycin is not readily transmitted by mosquitoes

Antimalarials are now used in combination with partner drugs to stem parasite drug resistance. Partners are often older, safe, cheap drugs, but resistance is already circulating for many, which raises the risk of selecting for multidrug resistance. If the partner drug(s) could be refractory to the spread of resistance, better resistance control could be implemented. We tested whether resistance to the antibiotic azithromycin, which kills malaria parasites by perturbing prokaryote-like protein synthesis in the apicoplast (relict plastid), had fitness costs to the spread of parasites via mosquitoes where parasites are not under drug pressure. Azithromycin resistance mutations in both rodent and human malaria parasites had a negative impact on the ability of resistant parasites to transmit from one vertebrate host to another via mosquitoes. Azithromycin resistance will therefore be less likely to spread geographically, making it an attractive option as a perennial partner compound to protect appropriate frontline antimalarials.

molecular biology↗

bioRxiv2023

Aryl amino acetamides prevent the development of Plasmodium falciparum rings via inhibition of the lipid transfer protein PfSTART1

With resistance to most antimalarials increasing, it is imperative that new antimalarial drugs are developed to replace or complement front-line artemisinin therapies. We previously identified an aryl acetamide compound, MMV006833 (M-833), that inhibited ring development of newly invaded merozoites. Here, we selected parasites resistant to M-833 and identified independent mutations arising in the START lipid transfer protein (PF3D7_0104200, PfSTART1). Introduction of the identified PfSTART1 mutations into wildtype parasites reproduced resistance to both M-833 and highly potent analogues, confirming PfSTART1 mutations were sufficient to confer resistance. The analogues bound to recombinant PfSTART1 with nanomolar affinity. We also demonstrated selective PfSTART1 engagement by the analogues using organic solvent-based Proteome Integral Solubility Alteration (Solvent PISA) assay for the first time in Plasmodium. Imaging of newly invaded merozoites showed the inhibitors prevented the conversion into larger amoeboid ring-stage parasites potentially through the inhibition of phospholipid transfer from the parasite to the encasing parasitophorous vacuole membrane (PVM) and/or within the parasite. We show that these PfSTART1 inhibitors also block transmission. With multiple stages of the parasites lifecycle being targeted by PfSTART1 inhibitors, this protein therefore represents a novel drug target with a new mechanism of action.

cell biology↗

bioRxiv2022

The sulfonylpiperazine MMV020291 prevents red blood cell invasion by the malaria parasite Plasmodium falciparum through interference with actin-1/profilin dynamics

With emerging resistance to frontline treatments, it is vital that new antimalarial drugs are identified to target Plasmodium falciparum. We have recently described a compound, MMV020291, as a specific inhibitor of red blood cell invasion, and have generated analogues with improved potency. Here, we identify actin and profilin as putative targets of the MMV020291 series through resistance selection and whole genome sequencing of three MMV020291 resistant populations. This revealed three non-synonymous single nucleotide polymorphisms in two genes; two in profilin (N154Y, K124N) and a third one in actin-1 (M356L). Using CRISPR-Cas9, we engineered these mutations into wildtype parasites which rendered them resistant to MMV020291. We demonstrate that MMV020291 reduces actin polymerisation that is required by the merozoite stage parasites to invade red blood cells. Additionally, the series inhibits the actin-1 dependent process of apicoplast segregation, leading to a delayed death phenotype. In vitro co-sedimentation experiments using recombinant P. falciparum actin-1 and profilin proteins indicate that potent MMV020291 analogues amplify the actin-monomer sequestering effect of profilin, thereby reducing the formation of filamentous actin. Altogether, this study identifies the first compound series targeting the actin-1/profilin interaction in P. falciparum and paves the way for future antimalarial development against the highly dynamic process of actin polymerisation.

molecular biology↗

bioRxiv2020

A single point mutation in the Plasmodium falciparum ftsh1 metalloprotease confers actinonin resistance.

The antibiotic actinonin kills malaria parasites (Plasmodium falciparum) by interfering with apicoplast function. Early evidence suggested that actinonin inhibited prokaryote-like post-translational modification in the apicoplast; mimicking its activity against bacteria. However, Amberg Johnson et al. (2017) identified the metalloprotease TgFtsH1 as the target of actinonin in the related parasite Toxoplasma gondii and implicated actinonin in the inhibition of P. falciparum growth. The authors were not, however, able to recover actinonin resistant malaria parasites, leaving the specific target of actinonin uncertain. We generated actinonin resistant P. falciparum by in vitro selection and identified a specific sequence change in PfftsH1 associated with resistance. Re-Introduction of this point mutation using CRISPr-Cas9 allelic replacement was sufficient to confer actinonin resistance in P. falciparum. Our data unequivocally identifies PfFtsH1 as the target of actinonin and suggests that actinonin should not be included in the highly valuable collection of "irresistible" drugs for combatting malaria.

microbiology↗