FIKK‐9.1 kinase is monomeric with a native molecular weight of 60 ± 1.6 kDa. The C‐terminal domain of protein has a well‐defined pocket to bind ATP. FIKK protein binds ATP with a K d of 45.6 ± 2.4 µM. FIKK‐9.1 has 23 pockets to serve potential docking sites for substrates. Peptide P277 is fitting nicely into the binding pocket. FIKK‐9.1 is phosphorylating spectrin, ankyrin, band 3 in the IRBC. FIKK 9.1 can be exploited in drug discovery and diagnostics.
Abstract
FIKK‐9.1 is essential for parasite survival, but its structural and biochemical characterization will enable us to understand its role in the parasite life cycle. The recombinant FIKK9.1 kinase is monomeric with a native molecular weight of 60 ± 1.6 kDa. Structural characterization of FIKK9.1 kinase reveals that it consists of two domains: N‐terminal FHA like domain and C‐terminal kinase domain. The C‐terminal domain has a well‐defined pocket, but it displayed RMSD deviation of 1.38–3.2 Å from host kinases. ITC analysis indicates that ATP binds to the protein with a K d of 45.6 ± 2.4 µM. Mutational studies confirm the role of Val‐244, Met‐245, Lys‐320, 324, and Glu‐366 for ATP binding. Co‐localization studies revealed FIKK9.1 in the parasite cytosol with a component trafficked to the apicoplast and also to IRBC. FIKK9.1 has 23 pockets to serve as potential docking sites for substrates. Correlation analysis of peptides from the combinatorial library concluded that peptide P277 (MFDFHYTLGPMWGTL) was fitting nicely into the binding pocket. The peptide P277 picked up candidates from parasite and key players from RBC cytoskeleton. Interestingly, FIKK9.1 is phosphorylating spectrin, ankyrin, and band‐3 from RBC cytoskeleton. Our study highlights the structural and biochemical features of FIKK9.1 to exploit it as a drug target.
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