Graduation Year

2023

Document Type

Dissertation

Degree

Ph.D.

Degree Name

Doctor of Philosophy (Ph.D.)

Degree Granting Department

Medical Sciences

Major Professor

John H. Adams, Ph.D.

Co-Major Professor

Andreas Seyfang, Ph.D.

Committee Member

Burt Anderson, Ph.D.

Committee Member

Liwang Cui, Ph.D.

Committee Member

Kami Kim, M.D.

Committee Member

Zhiming Ouyang, Ph.D.

Keywords

Drug Resistance, Genomics, Malaria, RNA Sequencing

Abstract

Malaria is a parasitic illness caused by the Plasmodium spp., with an estimated 247 million malaria cases reported in 2021 across 84 endemic countries. Treatment of the deadliest malaria parasite, P. falciparum, relies on artemisinin combination therapies (ACTs). However, while ACTs have greatly decreased malaria mortality, this progress is threatened due to artemisinin (ART) partial resistance and ACT failure in Southeast Asia and Sub-Saharan Africa. SNPs to the Kelch13 (K13) gene are a well-characterized marker for ART resistance. However, increasing evidence that resistance to ART mediated by genes not related to K13 SNPs prompts the need to characterize other novel genes that can alter ART responses. In previous chemogenomic profiling analyses of P. falciparum piggyBac mutants, several genes of unknown function exhibited increased sensitivity to ART that was similar to a mutant of K13. Therefore, we have characterized three of these ART sensitivity cluster genes and their associated piggyBac mutants to further elucidate the molecular activities associated with ART mediated parasite response mechanisms: the K13 interacting candidate 5 protein (protein KIC5), a previously conserved Plasmodium gene of unknown function now termed as a Modulator of Ring Stage Translation (MRST) protein, and a cysteine desulfurase NFS1 protein. KIC5 was found to be related with transcriptional changes to DNA stress response and mitochondrial metabolism, suggesting essentiality under ART exposure for wild-type stress response. We also found an association between MRST and expression of translation-associated pathways, suggesting an essential role of MRST in protein biosynthesis activities. Lastly, we identified a novel link between NFS1, [Fe-S] biogenesis, proteostasis, and fever response in the parasite. We have also characterized the shared transcriptional response of these three mutants, corroborating the role of the mitochondrial metabolism and protein translation regulation in parasite stress response. Overall, our findings introduce three key genes that may regulate P. falciparum stress response, provide an additional starting point for genomic characterization of parasite drug interactions, and contribute to a comprehensive understanding of parasite-drug molecular activities.

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