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An. R. Acad. Nac. Farm., 2006, 72: 629-642

Artículo original

Protein processing in Plasmodium falciparum?

Recibido el 28 de noviembre de 2006

ALMUDENA CROOKE, AZAR RADFAR, AMALIA DIEZ and
JOSÉ M. BAUTISTA *

Departmento de Bioquímica y Biología Molecular IV,
Universidad Complutense de Madrid, Facultad de Veterinaria,

Madrid (Spain)

ABSTRACT

The genomes from the organisms of the Plasmodium genus, the causative agents
of human and animal malaria, are characterized by an extreme high A+T content
and an associated abundant low complexity inserts within their proteins. The
enzyme glucose-6-phosphate dehydrogenase-6-phosphogluconolactonase (G6PD-
6PGL) found in Plasmodium species has unique structural and bifunctional
characteristics. Here, we report the expression analysis of P. faciparum G6PD-
6PGL along the intraerythrocytic cycle by immunological analysis with antibodies
raised against its N- and C- terminal domains. The pattern modification of band
sizes at the different stages of parasite development suggest intracellular protein
processing involving the cleavage of the native bifunctional form to produce two
main fragments. In vitro RNA-mediated PfG6PD-6PGL gene silencing, studied along
short-term parasite development also revealed the apparent intracellular protein
modification dependent on the parasite stage. Fragment sizes were consistent with
separating both catalytic functions of the enzyme. The proteolytic machinery
underlying this specific PfG6PD-6PGL proccesing is still unknown in P. falciparum
but suggests the existence of distinctive mechanisms in the parasite to deal with
unique protein structures of essential function resulting from its genome evolution.

* To whom correspondence should be addressed: José M. Bautista, Departamento
de Bioquímica y Biología Molecular IV, Universidad Complutense de Madrid, Facultad
de Veterinaria, Ciudad Universitaria, 28040 Madrid (Spain).

Tel: + 34 91 394 3823. Fax +34 91 394 3824, e-mail: jmbau@vet.ucm.es

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