scholarly journals Moving “Forward” inPlasmodiumGenetics through a Transposon-Based Approach

2012 ◽  
Vol 2012 ◽  
pp. 1-7 ◽  
Author(s):  
Bharath Balu

The genome sequence of the human malaria parasite,Plasmodium falciparum, was released almost a decade ago. A majority of thePlasmodiumgenome, however, remains annotated to code for hypothetical proteins with unknown functions. The introduction of forward genetics has provided novel means to gain a better understanding of gene functions and their associated phenotypes inPlasmodium. Even with certain limitations, the technique has already shown significant promise to increase our understanding of parasite biology needed for rationalized drug and vaccine design. Further improvements to the mutagenesis technique and the design of novel genetic screens should lead us to some exciting discoveries about the critical weaknesses ofPlasmodium, and greatly aid in the development of new disease intervention strategies.

Parasitology ◽  
2000 ◽  
Vol 121 (2) ◽  
pp. 127-133 ◽  
Author(s):  
T. G. SMITH ◽  
P. LOURENÇO ◽  
R. CARTER ◽  
D. WALLIKER ◽  
L. C. RANFORD-CARTWRIGHT

2005 ◽  
Vol 392 (1) ◽  
pp. 221-229 ◽  
Author(s):  
Keizo Yuasa ◽  
Fumika Mi-Ichi ◽  
Tamaki Kobayashi ◽  
Masaya Yamanouchi ◽  
Jun Kotera ◽  
...  

This is the first report of molecular characterization of a novel cyclic nucleotide PDE (phosphodiesterase), isolated from the human malaria parasite Plasmodium falciparum and designated PfPDE1. PfPDE1 cDNA encodes an 884-amino-acid protein, including six putative transmembrane domains in the N-terminus followed by a catalytic domain. The PfPDE1 gene is a single-copy gene consisting of two exons and a 170 bp intron. PfPDE1 transcripts were abundant in the ring form of the asexual blood stages of the parasite. The C-terminal catalytic domain of PfPDE1, produced in Escherichia coli, specifically hydrolysed cGMP with a Km value of 0.65 μM. Among the PDE inhibitors tested, a PDE5 inhibitor, zaprinast, was the most effective, having an IC50 value of 3.8 μM. The non-specific PDE inhibitors IBMX (3-isobutyl-1-methylxanthine), theophylline and the antimalarial chloroquine had IC50 values of over 100 μM. Membrane fractions prepared from P. falciparum at mixed asexual blood stages showed potent cGMP hydrolytic activity compared with cytosolic fractions. This hydrolytic activity was sensitive to zaprinast with an IC50 value of 4.1 μM, but insensitive to IBMX and theophylline. Furthermore, an in vitro antimalarial activity assay demonstrated that zaprinast inhibited the growth of the asexual blood parasites, with an ED50 value of 35 μM. The impact of cyclic nucleotide signalling on the cellular development of this parasite has previously been discussed. Thus this enzyme is suggested to be a novel potential target for the treatment of the disease malaria.


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