title: Transient silencing of Plasmodium falciparum bifunctional glucose-6-phosphate dehydrogenase- 6-phosphogluconolactonase.
abstract: The bifunctional enzyme glucose-6-phosphate dehydrogenase-6-phosphogluconolactonase (G6PD-6PGL) found in Plasmodium falciparum has unique structural and functional characteristics restricted to this genus. This study was designed to examine the effects of RNA-mediated PfG6PD-6PGL gene silencing in cultures of P. falciparum on the expression of parasite antioxidant defense genes at the transcription level. The highest degree of G6PD-6PGL silencing achieved was 86% at the mRNA level, with a recovery to almost normal levels within 24 h, indicating only transient diminished expression of the PfG6PD-6PGL gene. PfG6PD-6PGL silencing caused arrest of the trophozoite stage and enhanced gametocyte formation. In addition, an immediate transcriptional response was shown by thioredoxin reductase suggesting that P. falciparum G6PD-6PGL plays a physiological role in the specific response of the parasite to intracellullar oxidative stress. P. falciparum transfection with an empty DNA vector also promoted intracellular stress, as determined by mRNA up-regulation of antioxidant genes. Collectively, our findings point to an important role for this enzyme in the parasite's infection cycle. The different characteristics of G6PD-6PGL with respect to its homologue in the host make it an ideal target for therapeutic strategies.
authors.affiliation: Department of Biochemistry and Molecular Biology IV, Universidad Complutense de Madrid, Facultad de Veterinaria, Madrid, Spain.
authors.forename: Almudena
authors.initials: A
authors.lastname: Crooke
authors.forename: Amalia
authors.initials: A
authors.lastname: Diez
authors.forename: Philip J
authors.initials: PJ
authors.lastname: Mason
authors.forename: José M
authors.initials: JM
authors.lastname: Bautista
mesh_terms: D000818:Animals; D000975:Antioxidants / Q000378:metabolism; D002265:Carboxylic Ester Hydrolases / Q000235:genetics / Q000378:metabolism; D004912:Erythrocytes / Q000469:parasitology; D005786:Gene Expression Regulation; D020868:Gene Silencing; D005954:Glucosephosphate Dehydrogenase / Q000235:genetics / Q000378:metabolism; D006801:Humans; D016877:Oxidants / Q000378:metabolism; D018384:Oxidative Stress; D010963:Plasmodium falciparum / Q000737:chemistry / Q000201:enzymology* / Q000235:genetics*; D015800:Protozoan Proteins / Q000235:genetics / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism
chemical_list: D000975:Antioxidants; D016877:Oxidants; D015800:Protozoan Proteins; D012333:RNA, Messenger; D005954:Glucosephosphate Dehydrogenase; D002265:Carboxylic Ester Hydrolases; C022363:6-phosphogluconolactonase