RMgmDB - Rodent Malaria genetically modified Parasites


Malaria parasiteP. berghei
Genetic modification not successful
DisruptedGene model (rodent): PBANKA_0921300; Gene model (P.falciparum): PF3D7_1127100; Gene product: deoxyuridine 5'-triphosphate nucleotidohydrolase (dUTPase)
PhenotypeNo phenotype has been described
Last modified: 27 February 2019, 16:34
Successful modificationThe gene/parasite could not be changed/generated by the genetic modification.
The following genetic modifications were attempted Gene disruption
Number of attempts to introduce the genetic modification 3
Reference (PubMed-PMID number) Reference 1 (PMID number) : 30700216
Parent parasite used to introduce the genetic modification
Rodent Malaria ParasiteP. berghei
Parent strain/lineP. berghei ANKA
Name parent line/clone Not applicable
Other information parent line
Attempts to generate the mutant parasite were performed by
Name PI/ResearcherKumar H, Frischknecht F
Name Group/DepartmentIntegrative Parasitology, Department of Infectious Diseases
Name InstituteUniversity of Heidelberg Medical School

  Disrupted: Mutant parasite with a disrupted gene
Details of the target gene
Gene Model of Rodent Parasite PBANKA_0921300
Gene Model P. falciparum ortholog PF3D7_1127100
Gene productdeoxyuridine 5'-triphosphate nucleotidohydrolase
Gene product: Alternative namedUTPase
Details of the genetic modification
Inducable system usedNo
Additional remarks inducable system
Type of plasmid/construct used(Linear) plasmid double cross-over
PlasmoGEM (Sanger) construct/vector usedNo
Modified PlasmoGEM construct/vector usedNo
Plasmid/construct map
Plasmid/construct sequence
Restriction sites to linearize plasmid
Partial or complete disruption of the geneComplete
Additional remarks partial/complete disruption
Selectable marker used to select the mutant parasitehdhfr/yfcu
Promoter of the selectable markereef1a
Selection (positive) procedurepyrimethamine
Selection (negative) procedureNo
Additional remarks genetic modificationUnsuccessful attempts to delete dUTPase indicate an essential function during growth/multiplication of asexual blood stages.

In order to delete individual P. berghei house-cleaning genes (dUTPase: PBANKA_0921300, ITPase: PBANKA_0618300, Ap4AH: PBANKA_1235300, NDH: PBANKA_1361900), 5’UTR and 3’UTR regions were amplified from genomic DNA of mixed blood stages of P. berghei strain ANKA by polymerase chain reaction (PCR) using Phusion High-Fidelity DNA Polymerase (New England Biolabs, USA; fragments were digested with restriction endonucleases and ligated either side of the human dihydrofolate reductase, or a yeast bifunctional enzyme cytosine deaminase fused to a uridyl phosphoribosyl transferase (hdhfr-yFCU) as selection cassettes. Linearized vectors were transfected into purified schizonts of P. berghei ANKA using standard protocols.

Cellular metabolism generates reactive oxygen species. The oxidation and deamination of the deoxynucleoside triphosphate (dNTP) pool results in the formation of non-canonical, toxic dNTPs that can cause mutations, genome instability and cell death. House-cleaning or sanitation enzymes that break down and detoxify non-canonical nucleotides play major protective roles in nucleotide metabolism. In this paper 4 putative sanitation enzymes were identified using bioinformatic approaches ((dUTPase: PBANKA_0921300, ITPase: PBANKA_0618300, Ap4AH: PBANKA_1235300, NDH: PBANKA_1361900).

Based on structural features, sanitation enzymes belong to four superfamilies:

ITPases (inosine triphosphate pyrophosphatase) are defined by the Ham1 (6-n-HydroxylAMinopurine sensitive) domain consisting of a long central beta-sheet forming the floor of the active site;

dUTPases (deoxy-uridine triphosphatase) which present a trimeric fold, each with an eight-stranded jelly-roll beta barrel;

the NuDiX (nucleotide diphosphate linked to some other moiety, X) superfamily is defined by the NuDiX box domain G-x(5)-E-x(5)-[UA]-x-R-E-x(2)-E-E-x-G-U, where U is a hydrophobic residue and x any residue;

The fourth group contains all-α-helical NTPases which are active against dNTPs as well as dNDPs with the generation of dNMPs as an end product.

From the Abstract:
'While all four proteins are expressed constitutively across the intraerythrocytic developmental cycle, neither ITPase nor NDH are required for parasite viability. dutpase and ap4ah null mutants on the other hand are not viable suggesting an essential function for these proteins for the malaria parasite.

In order to address expression timing and localization we generated transgenic berghei parasite lines expressing each protein fused to green fluorescent protein (GFP) at its C-terminus. ap4ah and ndh were tagged at the endogenous loci, while we expressed dUTPase-GFP and ITPase-GFP episomally under the control of the native promoter using 986 and 865 basepairs of genomic sequence preceding each open reading frame, respectively. Protein expression in transfected parasites was followed by live microscopy and revealed a clear cytoplasmic GFP signal for all four proteins in asexual blood stages (ring, trophozoite and schizont) as well as gametocytes. Western blot analyses showed GFP-tagged dUTPase and ITPase to run higher than their expected molecular weights, while Ap4AH::GFP and NDH::GFP were detected at their predicted positions; NDH with a clear doublet and a smaller 25 kDa band correlating with the size of the cleaved GFP tag.
Additional remarks selection procedure
Primer information: Primers used for amplification of the target sequences  Click to view information
Primer information: Primers used for amplification of the target sequences  Click to hide information
Sequence Primer 1
Additional information primer 1
Sequence Primer 2
Additional information primer 2
Sequence Primer 3
Additional information primer 3
Sequence Primer 4
Additional information primer 4
Sequence Primer 5
Additional information primer 5
Sequence Primer 6
Additional information primer 6