A Preliminary Study on Possible Existence of Cytochrome P450 (CYP) Gene in Plasmodium Falciparum

Abstract

The existence of cytochrome P450 (CYP) enzymes in Plasmodium falciparum as well
as other protozoa may imply the role/function of CYP in parasite survival. Successful
hybridization of CYP-specific probes (CYP 2B1/B2) to P. falciparum mRNA extracted from
sensitive strains was reported. This evidence supported the existence of CYP genes in P.
falciparum malaria. In the present study, we characterized CYP gene in P. falciparum and
correlated CYP activities to antimalarial sensitivity in vitro. At the first step, an array of
bioinformatic technique was used to analyze all currently sequenced protozoan genomes
(http://www.sanger.ac.uk/ Projects/ Protozoa/) including Plasmodium spp., and with P.
falciparum in particular. The initial BLAST sequences with the conserved CYP gene were
performed, followed by more specific BLAST searches for sequences possessing CYP
homology of human and protozoan database. Results from BLAST analyses showed no
sequence alignments which would ascertain conserved nucleotide regions to be CYP gene in
P. falciparum. This contradictory finding confirmed the previous report. Phenobarbital was
added at 1 M concentration to the in vitro culture of early trophozoite stage P. falciparum
for both chloroquine-sensitive (3D7) and -resistant (K1) clones and the culture was incubated
at 37o C for 12 hr. Total RNA was isolated from the parasites and dot blot hybridization was
performed using a rat cDNA probe covering exon 6-9 of the phenobabitone inducible CYP
2B1/B2 gene. The negative result was shown in this experiment. Based on this result together
with the bioinformatics analyses, we suggested the absence of CYP 2B1/B2 gene in P.
falciparum genome.