| 1. |
- Billker, Oliver, et al.
(författare)
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Calcium and a calcium-dependent protein kinase regulate gamete formation and mosquito transmission in a malaria parasite
- 2004
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Ingår i: Cell. - : Elsevier. - 0092-8674 .- 1097-4172. ; 117:4, s. 503-514
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Tidskriftsartikel (refereegranskat)abstract
- Transmission of malaria parasites to mosquitoes is initiated by the obligatory sexual reproduction of the parasite within the mosquito bloodmeal. Differentiation of specialized transmission stages, the gametocytes, into male and female gametes is induced by a small mosquito molecule, xanthurenic acid (XA). Using a Plasmodium berghei strain expressing a bioluminescent calcium sensor, we show that XA triggers a rapid rise in cytosolic calcium specifically in gametocytes that is essential for their differentiation into gametes. A member of a family of plant-like calcium dependent protein kinases, CDPK4, is identified as the molecular switch that translates the XA-induced calcium signal into a cellular response by regulating cell cycle progression in the male gametocyte. CDPK4 is shown to be essential for the sexual reproduction and mosquito transmission of P. berghei. This study reveals an unexpected function for a plant-like signaling pathway in cell cycle regulation and life cycle progression of a malaria parasite.
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| 2. |
- Bushell, Ellen, et al.
(författare)
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Functional Profiling of a Plasmodium Genome Reveals an Abundance of Essential Genes
- 2017
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Ingår i: Cell. - : Cell Press. - 0092-8674 .- 1097-4172. ; 170:2, s. 260-272.e1-e4
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Tidskriftsartikel (refereegranskat)abstract
- The genomes of malaria parasites contain many genes of unknown function. To assist drug development through the identification of essential genes and pathways, we have measured competitive growth rates in mice of 2,578 barcoded Plasmodium berghei knockout mutants, representing >50% of the genome, and created a phenotype database. At a single stage of its complex life cycle, P. berghei requires two-thirds of genes for optimal growth, the highest proportion reported from any organism and a probable consequence of functional optimization necessitated by genomic reductions during the evolution of parasitism. In contrast, extreme functional redundancy has evolved among expanded gene families operating at the parasite-host interface. The level of genetic redundancy in a single-celled organism may thus reflect the degree of environmental variation it experiences. In the case of Plasmodium parasites, this helps rationalize both the relative successes of drugs and the greater difficulty of making an effective vaccine.
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| 3. |
- Stanway, Rebecca R., et al.
(författare)
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Genome-Scale Identification of Essential Metabolic Processes for Targeting the Plasmodium Liver Stage
- 2019
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Ingår i: Cell. - : Elsevier. - 0092-8674 .- 1097-4172. ; 179:5, s. 1112-1128.e1-e15
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Tidskriftsartikel (refereegranskat)abstract
- Plasmodium gene functions in mosquito and liver stages remain poorly characterized due to limitations in the throughput of phenotyping at these stages. To fill this gap, we followed more than 1,300 barcoded P. berghei mutants through the life cycle. We discover 461 genes required for efficient parasite transmission to mosquitoes through the liver stage and back into the bloodstream of mice. We analyze the screen in the context of genomic, transcriptomic, and metabolomic data by building a thermodynamic model of P. berghei liver-stage metabolism, which shows a major reprogramming of parasite metabolism to achieve rapid growth in the liver. We identify seven metabolic subsystems that become essential at the liver stages compared with asexual blood stages: type II fatty acid synthesis and elongation (FAE), tricarboxylic acid, amino sugar, heme, lipoate, and shikimate metabolism. Selected predictions from the model are individually validated in single mutants to provide future targets for drug development.
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