Identification, molecular cloning and functional characterization of an octaprenyl pyrophosphate synthase in intra-erythrocytic stages of Plasmodium falciparum.
Isoprenoids play important roles in all living organisms as components of structural cholesterol, steroid hormones in mammals, carotenoids in plants, and ubiquinones. Significant differences occur in the length of the isoprenic side chains of ubiquinone between different organisms, suggesting that different enzymes are involved in the synthesis of these side chains. Whereas in Plasmodium falciparum the isoprenic side chains of ubiquinone contain 7-9 isoprenic units, 10-unit side chains are found in humans. In a search for the P. falciparum enzyme responsible for the biosynthesis of isoprenic side chains attached to the benzoquinone ring of ubiquinones, we cloned and expressed a putative polyprenyl synthase. Polyclonal antibodies raised against the corresponding recombinant protein confirmed the presence of the native protein in trophozoite and schizont stages of P. falciparum. The recombinant protein, as well as P. falciparum extracts, showed an octaprenyl pyrophosphate synthase activity, with the formation of a polyisoprenoid with eight isoprenic units, as detected by reverse-phase HPLC and reverse-phase TLC, and confirmed by electrospray ionization and tandem MS analysis. The recombinant and native versions of the enzyme had similar Michaelis constants with the substrates isopentenyl pyrophosphate and farnesyl pyrophosphate. The recombinant enzyme could be competitively inhibited in the presence of the terpene nerolidol. This is the first report that directly demonstrates an octaprenyl pyrophosphate synthase activity in parasitic protozoa. Given the rather low similarity of the P. falciparum enzyme to its human counterpart, decaprenyl pyrophosphate synthase, we suggest that the identified enzyme and its recombinant version could be exploited in the screening of novel drugs.
Department of Parasitology, Institute of Biomedical Sciences, University of São Paulo, 05508-900 São Paulo, Brazil.
Renata
R
Tonhosolo
Fabio L
FL
D'Alexandri
Fernando A
FA
Genta
Gerhard
G
Wunderlich
Fabio C
FC
Gozzo
Marcos N
MN
Eberlin
Valnice J
VJ
Peres
Emilia A
EA
Kimura
Alejandro M
AM
Katzin
D019883:Alkyl and Aryl Transferases / Q000037:antagonists & inhibitors / Q000235:genetics* / Q000378:metabolism*; D000595:Amino Acid Sequence; D000818:Animals; D003001:Cloning, Molecular; D018507:Gene Expression Regulation, Developmental; D015971:Gene Expression Regulation, Enzymologic; D008969:Molecular Sequence Data; D010963:Plasmodium falciparum / Q000187:drug effects / Q000201:enzymology* / Q000254:growth & development*; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D012717:Sesquiterpenes / Q000494:pharmacology; D013379:Substrate Specificity
D012717:Sesquiterpenes; D019883:Alkyl and Aryl Transferases; C048987:octaprenyl pyrophosphate synthetase; C037055:nerolidol