scholarly journals NADPH production by the malarial parasite Plasmodium falciparum

Blood ◽  
1989 ◽  
Vol 74 (1) ◽  
pp. 471-474 ◽  
Author(s):  
DL Vander Jagt ◽  
LA Hunsaker ◽  
M Kibirige ◽  
NM Campos
Keyword(s):  
Plasmodium Falciparum ◽  
Molecular Mass ◽  
Host Cell ◽  
Isocitrate Dehydrogenase ◽  
Malarial Parasite ◽  
Developmental Cycle ◽  
Optimum Conditions ◽  
Ph Optimum ◽  
Parasite Plasmodium ◽  
Parasite Plasmodium Falciparum

Abstract Two enzymes from Plasmodium falciparum that catalyze the formation of NADPH have been partially purified and characterized. Glutamate dehydrogenase (GDH), molecular mass 230 Kd, pH optimum 7.0, is capable of producing NADPH under optimum conditions at about 10% of the capacity of the host erythrocyte. This capacity increases slightly during the developmental cycle of the parasite. NADP-specific isocitrate dehydrogenase (IDH), molecular mass 80 Kd, pH optimum 7.5, is capable of producing NADPH at 20% to 60% of the capacity of the host cell, depending on the developmental stage of the parasite. Increasing IDH activity is observed as the parasite matures. GDH and IDH provide the parasite with NADPH-generating abilities that compare favorably with the host cell.

scholarly journals NADPH production by the malarial parasite Plasmodium falciparum

Blood ◽  
1989 ◽  
Vol 74 (1) ◽  
pp. 471-474
Author(s):  
DL Vander Jagt ◽  
LA Hunsaker ◽  
M Kibirige ◽  
NM Campos
Keyword(s):  
Plasmodium Falciparum ◽  
Molecular Mass ◽  
Host Cell ◽  
Isocitrate Dehydrogenase ◽  
Malarial Parasite ◽  
Developmental Cycle ◽  
Optimum Conditions ◽  
Ph Optimum ◽  
Parasite Plasmodium ◽  
Parasite Plasmodium Falciparum

Two enzymes from Plasmodium falciparum that catalyze the formation of NADPH have been partially purified and characterized. Glutamate dehydrogenase (GDH), molecular mass 230 Kd, pH optimum 7.0, is capable of producing NADPH under optimum conditions at about 10% of the capacity of the host erythrocyte. This capacity increases slightly during the developmental cycle of the parasite. NADP-specific isocitrate dehydrogenase (IDH), molecular mass 80 Kd, pH optimum 7.5, is capable of producing NADPH at 20% to 60% of the capacity of the host cell, depending on the developmental stage of the parasite. Increasing IDH activity is observed as the parasite matures. GDH and IDH provide the parasite with NADPH-generating abilities that compare favorably with the host cell.

scholarly journals Inhibitory effects of erythrocyte membrane proteins on the in vitro invasion of the human malarial parasite (Plasmodium falciparum) into its host cell.

1981 ◽  
Vol 90 (3) ◽  
pp. 563-567 ◽  
Author(s):  
M Perkins
Keyword(s):  
Plasmodium Falciparum ◽  
Membrane Proteins ◽  
Host Cell ◽  
Malarial Parasite ◽  
Glycophorin A ◽  
Low Concentrations ◽  
Parasite Plasmodium ◽  
Erythrocyte Surface ◽  
Parasite Plasmodium Falciparum

The intracellular development of the erythrocytic stage of the malarial parasite (merozoite) is initiated by the attachment of the parasite to the erythrocyte surface. This paper describes an assay system to investigate Plasmodium falciparum merozoite entry into the host cell and reports on three observations regarding this interaction. (a) Merozoites do not invade human erythrocytes treated with either trypsin or neuraminidase, and both enzymes partially cleave glycophorin A, the major erythrocyte surface sialoglycoprotein. (b) A membrane protein fraction containing glycophorin A will, at low concentrations, inhibit the invasion of isolated merozoites into erythrocytes; no other fractions of membrane proteins have appreciable effects on the reinvasion. (c) Merozoites do not reinvade erythrocytes preincubated with F ab' fragments of antibody prepared against glycophorin A. Together, these three observations imply a role for glycophorin A in the attachment of the malarial parasite to the erythrocyte surface.

scholarly journals Localization of ferrochelatase in Plasmodium falciparum

2004 ◽  
Vol 384 (2) ◽  
pp. 429-436 ◽  
Author(s):  
Sundaramurthy VARADHARAJAN ◽  
B. K. Chandrashekar SAGAR ◽  
Pundi N. RANGARAJAN ◽  
Govindarajan PADMANABAN
Keyword(s):  
Plasmodium Falciparum ◽  
De Novo ◽  
Enzymic Activity ◽  
Malarial Parasite ◽  
Parasite Genome ◽  
Marker Proteins ◽  
Parasite Plasmodium ◽  
Theoretical Predictions ◽  
Parasite Plasmodium Falciparum

Our previous studies have demonstrated de novo haem biosynthesis in the malarial parasite (Plasmodium falciparum and P. berghei). It has also been shown that the first enzyme of the pathway is the parasite genome-coded ALA (δ-aminolaevulinate) synthase localized in the parasite mitochondrion, whereas the second enzyme, ALAD (ALA dehydratase), is accounted for by two species: one species imported from the host red blood cell into the parasite cytosol and another parasite genome-coded species in the apicoplast. In the present study, specific antibodies have been raised to PfFC (parasite genome-coded ferrochelatase), the terminal enzyme of the haem-biosynthetic pathway, using recombinant truncated protein. With the use of these antibodies as well as those against the hFC (host red cell ferrochelatase) and other marker proteins, immunofluorescence studies were performed. The results reveal that P. falciparum in culture manifests a broad distribution of hFC and a localized distribution of PfFC in the parasite. However, PfFC is not localized to the parasite mitochondrion. Immunoelectron-microscopy studies reveal that PfFC is indeed localized to the apicoplast, whereas hFC is distributed in the parasite cytoplasm. These results on the localization of PfFC are unexpected and are at variance with theoretical predictions based on leader sequence analysis. Biochemical studies using the parasite cytosolic and organellar fractions reveal that the cytosol containing hFC accounts for 80% of FC enzymic activity, whereas the organellar fraction containing PfFC accounts for the remaining 20%. Interestingly, both the isolated cytosolic and organellar fractions are capable of independent haem synthesis in vitro from [4-14C]ALA, with the cytosol being three times more efficient compared with the organellar fraction. With [2-14C]glycine, most of the haem is synthesized in the organellar fraction. Thus haem is synthesized in two independent compartments: in the cytosol, using the imported host enzymes, and in the organellar fractions, using the parasite genome-coded enzymes.

scholarly journals Refining the transcriptome of the human malaria parasite Plasmodium falciparum using amplification-free RNA-seq

2019 ◽  
Author(s):  
Lia Chappell ◽  
Philipp Ross ◽  
Lindsey Orchard ◽  
Thomas D. Otto ◽  
Matthew Berriman ◽  
...  
Keyword(s):  
Plasmodium Falciparum ◽  
Malaria Parasite ◽  
Developmental Cycle ◽  
Rna Seq ◽  
Human Malaria Parasite ◽  
Human Malaria ◽  
Parasite Plasmodium ◽  
Parasite Plasmodium Falciparum ◽  
Intraerythrocytic Developmental Cycle ◽  
Transcriptional Start Sites

AbstractPlasmodium parasites undergo several major developmental transitions during their complex lifecycle, which are enabled by precisely ordered gene expression programs. Transcriptomes from the 48-hour blood stages of the major human malaria parasite Plasmodium falciparum have been described using cDNA microarrays and RNA-seq, but these assays have not always performed well within non-coding regions, where the AT-content is often 90-95%. We developed a directional, amplification-free RNA-seq protocol (DAFT-seq) to reduce bias against AT-rich cDNA, which we have applied to three strains of P. falciparum (3D7, HB3 and IT). While strain-specific differences were detected, overall there is strong conservation between the transcriptional profiles. For the 3D7 reference strain, transcription was detected from 89% of the genome, with over 75% of the genome transcribed into mRNAs. These datasets allowed us to refine the 5’ and 3’ untranslated regions (UTRs), which can be variable, long (>1,000 nt), and often overlap those of adjacent transcripts. We also find that transcription from bidirectional promoters frequently results in non-coding, antisense transcripts. By capturing the 5’ ends of mRNAs, we reveal both constant and dynamic use of transcriptional start sites across the intraerythrocytic developmental cycle resulting in an updated view of the P. falciparum transcriptome.

scholarly journals Molecular cloning, characterization and localization of PfPK4, an eIF-2α kinase-related enzyme from the malarial parasite Plasmodium falciparum

1997 ◽  
Vol 328 (2) ◽  
pp. 677-687 ◽  
Author(s):  
Jörg J. MÖHRLE ◽  
Yi ZHAO ◽  
Barbara WERNLI ◽  
M. Richard FRANKLIN ◽  
Barbara KAPPES
Keyword(s):  
Amino Acids ◽  
Plasmodium Falciparum ◽  
Protein Kinase ◽  
Protein Kinases ◽  
Initiation Factor ◽  
Malarial Parasite ◽  
Kinase Gene ◽  
Western Blots ◽  
Parasite Plasmodium ◽  
Parasite Plasmodium Falciparum

PfPK4, a protein kinase gene from the human malarial parasite Plasmodium falciparum, has been cloned utilizing oligonucleotide probing. The gene encodes a protein of a predicted length of 1123 amino acids, and within this amino acid sequence all the conserved regions characteristic of protein kinases can be identified. The catalytic kinase domain possesses highest identities (34-37%) with eukaryotic initiation factor-2α (eIF-2α) kinases, especially haem-regulated inhibitory (HRI) protein kinases. There are two kinase inserts in PfPK4, located at positions common to eIF-2α kinases. The first insert separates kinase subdomains IV and VI by 559 amino acids, and the second subdomains VII and VIII by 41 amino acids. Both inserts are larger than their homologues in eIF-2α kinases. The sequence of PfPK4 has one putative haemin-binding site. The recombinant protein, expressed in Escherichia coli, phosphorylates a synthetic peptide representing a substrate of eIF-2α kinases. Autophosphorylation and substrate phosphorylation are inhibited by haemin. Thus PfPK4 appears to be the first protozoan protein kinase related to eIF-2α kinases and might be the first non-mammalian HRI kinase. Western blots indicated that the protein is expressed as major forms of 80 and 90 kDa. Whereas the 80 kDa form is present throughout the intraerythrocytic development and in merozoites, the two 90 kDa forms are only found in mature parasites. One of the latter is also present in the membrane fraction of erythrocytes harbouring segmenters. Confocal microscopy detected the protein distributed throughout the trophozoite, whereas it was found in discrete foci (punctate distribution) in segmenters. PfPK4 co-localizes with P. falciparum 83 kDa antigen/apical membrane antigen-1 at the apical complex in segmenters and merozoites, but does not co-localize with rhoptry-associated protein-1.

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