Characterization of two T. gondii CK1 isoforms

Area of Science:

• Parasitology
• Molecular Biology
• Biochemistry

Background:

• Casein kinase I (CK1) isoforms from various parasites unexpectedly bind to cyclin-dependent kinase (CDK) inhibitors.
• This suggests CK1 could be a potential anti-parasitic drug target.

Purpose of the Study:

• To investigate the role of two Toxoplasma gondii CK1 genes (TgCK1alpha and TgCK1beta) as potential anti-parasitic targets.
• To characterize the biochemical and cellular properties of these isoforms.

Main Methods:

• Polymerase chain reaction (PCR) was used to clone two T. gondii CK1 genes.
• Recombinant TgCK1alpha and TgCK1beta were expressed and purified.
• Immunoprecipitation and deletion mapping were used to determine protein localization.
• Biochemical characterization and partial purification of native CK1 activity from tachyzoites were performed.
• Enzyme inhibition assays were conducted using purvalanol B and aminopurvalanol A.

Main Results:

• Two T. gondii CK1 genes were cloned, encoding 38 kDa (TgCK1alpha) and 49 kDa (TgCK1beta) isoforms.
• Recombinant TgCK1alpha localized to the cytosol, while TgCK1beta localized to the plasma membrane.
• Native 38 kDa CK1 activity in tachyzoites matched recombinant TgCK1alpha.
• TgCK1beta activity was not detected in tachyzoite lysates.
• Purvalanol B and aminopurvalanol A selectively inhibited TgCK1alpha.
• Aminopurvalanol inhibited parasite growth.

Conclusions:

• TgCK1alpha is a cytosolic enzyme, while TgCK1beta is membrane-associated.
• TgCK1alpha is a potential anti-parasitic drug target.
• Selective CK1 inhibitors show promise for treating parasitic infections.