title: Characterization of coproporphyrinogen III oxidase in Plasmodium falciparum cytosol.
abstract: A unique hybrid pathway has been proposed for de novo heme biosynthesis in Plasmodium falciparum involving three different compartments of the parasite, namely mitochondrion, apicoplast and cytosol. While parasite mitochondrion and apicoplast have been shown to harbor key enzymes of the pathway, there has been no experimental evidence for the involvement of parasite cytosol in heme biosynthesis. In this study, a recombinant P. falciparum coproporphyrinogen III oxidase (rPfCPO) was produced in E. coli and confirmed to be active under aerobic conditions. rPfCPO behaved as a monomer of 61kDa molecular mass in gel filtration analysis. Immunofluorescence studies using antibodies to rPfCPO suggested that the enzyme was present in the parasite cytosol. These results were confirmed by detection of enzyme activity only in the parasite soluble fraction. Western blot analysis with anti-rPfCPO antibodies also revealed a 58kDa protein only in this fraction and not in the membrane fraction. The cytosolic presence of PfCPO provides evidence for a hybrid heme-biosynthetic pathway in the malarial parasite.
authors.affiliation: Department of Biochemistry, Indian Institute of Science, Bangalore, India.
authors.forename: Viswanathan Arun
authors.initials: VA
authors.lastname: Nagaraj
authors.forename: Dasari
authors.initials: D
authors.lastname: Prasad
authors.forename: Rajavel
authors.initials: R
authors.lastname: Arumugam
authors.forename: Pundi N
authors.initials: PN
authors.lastname: Rangarajan
authors.forename: Govindarajan
authors.initials: G
authors.lastname: Padmanaban
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D015153:Blotting, Western; D003001:Cloning, Molecular; D003304:Coproporphyrinogen Oxidase / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism; D003600:Cytosol / Q000201:enzymology* / Q000378:metabolism; D004912:Erythrocytes / Q000469:parasitology; D006418:Heme / Q000096:biosynthesis; D006801:Humans; D008856:Microscopy, Fluorescence; D008969:Molecular Sequence Data; D010963:Plasmodium falciparum / Q000201:enzymology* / Q000235:genetics; D015800:Protozoan Proteins / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism; D016415:Sequence Alignment
chemical_list: D015800:Protozoan Proteins; D011994:Recombinant Proteins; D006418:Heme; D003304:Coproporphyrinogen Oxidase