Pharmacological targeting of mRNA cap formation for treatment of parasitic infections

A method of screening for a compound that inhibits the catalytic activity of Plasmodium guanylyltransferase, comprising the steps of:

• contacting said guanylyltransferase with a guanosine triphosphate substrate and a divalent cation cofactor in the presence or absence of said compound;
• and
• detecting formation of a covalent guanylyltransferase-GMP intermediate, wherein a lack of formation of said intermediate or a decrease in formation of said intermediate indicates said compound inhibits the catalytic activity of said guanylyltransferase.

A method of screening for a compound that inhibits the catalytic activity of Plasmodium guanylyltransferase, comprising the steps of:

• contacting said Plasmodium guanylyltransferase with a guanosine triphosphate substrate and a divalent cation cofactor and a diphosphate-terminated RNA in the presence or absence of said compound;
• and
• detecting formation of a GMP-capped RNA, wherein a lack of formation of said GMP-capped RNA or a decrease in formation of said GMP-capped RNA indicates said compound inhibits the catalytic activity of said guanylyltransferase.

An isolated DNA encoding a mRNA capping enzyme RNA 5′ triphosphatase of Plasmodium falciparum, wherein the amino acid sequence of said enzyme is shown in SEQ ID No. 2.

A method of screening for a compound that inhibits the catalytic activity of the RNA 5′ triphosphatase component of the mRNA capping apparatus of a unicellular eukaryotic parasite, comprising the steps of:

• contacting said unicellular parasite-encoded RNA 5′ triphosphatase with a nucleoside triphosphate substrate and a divalent cation cofactor in the presence or absence of said compound;
• and
• detecting hydrolysis of said nucleoside triphosphate to a nucleoside diphosphate and inorganic phosphate, wherein a lack of hydrolysis of said nucleoside triphosphate or a decrease in hydrolysis of said nucleoside triphosphate indicates said compound inhibits the catalytic activity of said parasite-encoded triphosphatase.

A method of screening for a compound that inhibits the catalytic activity of the RNA 5′ triphosphatase component of the mRNA capping apparatus of a unicellular eukaryotic parasite comprising the steps of:

• contacting said unicellular parasite-encoded triphosphatase with a 5′ triphosphate RNA substrate and a divalent cation cofactor in the presence or absence of said compound;
• and
• detecting hydrolysis of said triphosphate RNA to a diphosphate RNA and inorganic phosphate, wherein a lack of hydrolysis of said triphosphate RNA or a decrease in hydrolysis of said triphosphate RNA indicates said compound inhibits the catalytic activity of said parasite-encoded triphosphatase.