Successful modification | The parasite was generated by the genetic modification |
The mutant contains the following genetic modification(s) |
Gene disruption
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Reference (PubMed-PMID number) |
Reference 1 (PMID number) : 22628552 |
MR4 number |
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Parent parasite used to introduce the genetic modification |
Rodent Malaria Parasite | P. berghei |
Parent strain/line | P. berghei ANKA |
Name parent line/clone |
P. berghei ANKA 2.34
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Other information parent line | P. berghei ANKA 2.34 is a cloned, gametocyte producer line of the ANKA strain (PubMed: PMID: 15137943). |
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The mutant parasite was generated by |
Name PI/Researcher | A. Hino; K. Kita |
Name Group/Department | Department of Biomedical Chemistry |
Name Institute | Graduate School of Medicine, The University of Tokyo |
City | Tokyo |
Country | Japan |
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Name of the mutant parasite |
RMgm number | RMgm-753 |
Principal name | Pbsdha(-) |
Alternative name | |
Standardized name | |
Is the mutant parasite cloned after genetic modification | Yes |
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Phenotype |
Asexual blood stage | Not different from wild type |
Gametocyte/Gamete | Normal numbers of gametocytes are produced and male gamete formation (exflagellation) was normal. The conversion rate of female gametes to ookinetes in vitro of Pbsdha(-) was significantly reduced to 17% of wild type parasites. |
Fertilization and ookinete | The conversion rate of female gametes to ookinetes in vitro of Pbsdha(-) was significantly reduced to 17% of wild type parasites. |
Oocyst | The conversion rate of female gametes to ookinetes in vitro of Pbsdha(-) was significantly reduced to 17% of wild type parasites.
No oocysts are formed. |
Sporozoite | Not tested |
Liver stage | Not tested |
Additional remarks phenotype | Mutant/mutation
The mutant lacks expression of flavoprotein subunit of succinate dehydrogenase (SDHA)
Protein (function)
In other eukaryotes, pyruvate dehydrogenase is localized in mitochondria where it links the glycolysis metabolic pathway to TCA cycle, while it is localized in the apicoplast in P. falciparum. Blood-stage P. falciparum have only a single mitochondrion without crista. Such morphologically immature mitochondrion suggests that, unlike other eukaryotes, the blood-stage P. falciparum relies mainly on cytoplasmic glycolysis for their energy metabolism but not on mitochondrial oxidative phosphorylation. P. falciparum express all TCA cycle enzyme genes and most ones for the electron transport chain (ETC). The genes for TCA cycle are up-regulated at mosquito stages. The gametocytes, precursor cells of gametes possess mitochondria with cristae. These data suggest that mitochondrial energy metabolism may have more crucial roles in insect stages than blood stages. The mitochondrial complex II (succinate-ubiquinone reductase: SQR) oxidizes succinate to produce fumarate as a TCA cycle member enzyme. In the anaerobic electron transfer system, complex II carries out fumarate reduction using quinol as an electron donor (quinol-fumarate reductase; QFR), which is the reverse reaction of SQR. Complex II consists of four subunits, flavoprotein (Fp), iron-sulfur cluster protein (Ip) and two small membrane anchor subunits, cytochrome b large (CybL) and small (CybS) subunits. The Fp with molecular mass of 70 kDa has a flavin adenine dinucleotide (FAD) covalently bound to a highly conserved histidine (His) residue. Fp and Ip form catalytic portion of the complex and this portion act as a succinate dehydrogenase (SDH), catalyzing the oxidation of succinate by water-soluble electron acceptors such as phenazine methosulfate (PMS) in SQR, while it acts as a fumarate reductase (FRD), catalyzing electron transfer from water-soluble electron donors such as reduced methylviologen (MV) to fumarate in QFR. FAD in the Fp receives the reducing equivalents from succinate and then transfers it to quinone by SQR activity where the two small membrane anchor subunits are indispensable (10). Thus, complex II functions as a link between the TCA cycle and the ETC, directly. While complex II has such critical roles in energy metabolisms and Fp and Ip subunits genes are substantially conserved in various organisms, two small membrane anchor subunit genes are diverse. However, evidence for the presence of genes in the Plasmodium genome encoding mitochondrial Complex II subunits SDH3 and SDH4 and ATP synthase subunits a and b.
Phenotype
Phenotype analyses indicate a non-essential function of SDHA for asexual blood stages.
Phenotype analyses indicate an essential function of SDHA for ookinete and/or oocyst formation. Normal numbers of gametocytes are produced and male gamete formation (exflagellation) is normal. The conversion rate of female gametes to ookinetes in vitro of Pbsdha(-) is significantly reduced to 17% of wild type parasites. No oocysts are formed.
Additional information
Other mutants
RMgm-754: A mutant expressing GFP under control of the 5'- and 3'-UTR region of sdha and fused to the first 60 amino acids of sdha
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