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Primary structure of the Plasmodium vivax crk2 gene and interference of the yeast cell cycle upon its conditional
M A Sperança1, R Vinkenoog, M Ocampos
1Departamento de Parasitologia, Instituto de Ciências Biomédicas, 05508-900 São Paulo, SP, Brazil.
Abstract:
The cdc2 gene product, a 34-kDa protein kinase, plays a universal role in the M phase of the eukaryotic cell cycle. To study the cell cycle regulation in malarial parasites, we have characterized a cdc2-related gene from the most widely distributed human malaria, Plasmodium vivax (Pvcrk2). The full-length Pvcrk2 revealed 90--99% homology with Crk2 proteins from other Plasmodium species and approximately 60% homology with p34(cdc2) proteins from higher eukaryotes. We used the temperature-sensitive Schizosaccharomyces pombe cdc2 mutant (cdc2-33(ts)) for gene complementation studies. Expression of the full-length 33-kDa PvCrk2 protein, a truncated 27-kDa version, and two chimeric proteins in which we exchanged the N- and C-terminal regions of PvCrk2 with their S. pombe counterparts at the restrictive temperature in the mutant cdc2-33(ts) did not complement the cell cycle defect. However, conditional expression of the Pvcrk2 genes or the chimera containing the C terminus from Spcdc2 in mutant cdc2-33(ts) cells produced cell-cycle-arrested phenotypes only in the induced state and at the permissive temperature. Our results thus provide the first compelling genetic evidence that the plasmodial Crk2 gene product(s) is capable of interfering with the well-conserved eukaryotic cell cycle machinery.
Insights
The Plasmodium vivax cdc2-related kinase 2 (Pvcrk2) gene product can interfere with the eukaryotic cell cycle. Genetic studies show Pvcrk2 can disrupt cell cycle progression in yeast, offering insights into malaria parasite regulation.
Area of Science:
- Cell Biology
- Parasitology
- Molecular Biology
Background:
- The cdc2 gene product is a 34-kDa protein kinase crucial for M phase in eukaryotic cell cycles.
- Understanding cell cycle regulation in malaria parasites is vital for developing new therapies.
Purpose of the Study:
- To characterize the cdc2-related gene Pvcrk2 from Plasmodium vivax.
- To investigate the functional role of Pvcrk2 in eukaryotic cell cycle machinery.
Main Methods:
- Gene characterization of Pvcrk2 from Plasmodium vivax.
- Gene complementation studies using a temperature-sensitive Schizosaccharomyces pombe cdc2 mutant (cdc2-33(ts)).
- Expression of full-length, truncated, and chimeric Pvcrk2 proteins in the yeast mutant.
Main Results:
- Pvcrk2 shares high homology with Crk2 proteins in other Plasmodium species and moderate homology with higher eukaryote p34(cdc2).
- Expression of Pvcrk2 or chimeric proteins did not complement the yeast cell cycle defect at the restrictive temperature.
- Conditional expression of Pvcrk2 or a specific chimera induced cell cycle arrest in the yeast mutant under specific conditions.
Conclusions:
- Provides the first compelling genetic evidence for the plasmodial Crk2 gene product's ability to interfere with conserved eukaryotic cell cycle machinery.
- Suggests that Plasmodium Crk2 proteins can interact with and disrupt fundamental cell cycle processes.