Calcium-dependent protein kinases (CDPKs) have pivotal roles in the calcium-signaling pathway in plants, ciliates and apicomplexan parasites and comprise a calmodulin-dependent kinase (CaMK)-like kinase domain regulated by a calcium-binding domain in the C terminus. To understand this intramolecular mechanism of activation, we solved the structures of the autoinhibited (apo) and activated (calcium-bound) conformations of CDPKs from the apicomplexan parasites Toxoplasma gondii and Cryptosporidium parvum. In the apo form, the C-terminal CDPK activation domain (CAD) resembles a calmodulin protein with an unexpected long helix in the N terminus that inhibits the kinase domain in the same manner as CaMKII. Calcium binding triggers the reorganization of the CAD into a highly intricate fold, leading to its relocation around the base of the kinase domain to a site remote from the substrate binding site. This large conformational change constitutes a distinct mechanism in calcium signal-transduction pathways.
At a glance
- Intracellular parasite invasion strategies. Science 304, 248–253 (2004).
- Calcium regulation and signaling in apicomplexan parasites. Subcell. Biochem. 47, 70–81 (2008). , , &
- Structure of the autoinhibited kinase domain of CaMKII and SAXS analysis of the holoenzyme. Cell 123, 849–860 (2005). et al.
- Calcium-dependent signaling and kinases in apicomplexan parasites. Cell Host Microbe 5, 612–622 (2009). , &
- Novel structural and regulatory features of rhoptry secretory kinases in Toxoplasma gondii . EMBO J. 28, 969–979 (2009). et al.
- The crystal structure of a c-Src complex in an active conformation suggests possible steps in c-Src activation. Structure 13, 861–871 (2005). et al.
- Structural basis for the autoinhibition of c-Abl tyrosine kinase. Cell 112, 859–871 (2003). et al.
- Structure of the regulatory apparatus of a calcium-dependent protein kinase (CDPK): a novel mode of calmodulin-target recognition. J. Mol. Biol. 357, 400–410 (2006). et al.
- Evidence for differing roles for each lobe of the calmodulin-like domain in a calcium-dependent protein kinase. J. Biol. Chem. 279, 29092–29100 (2004). , , &
- Calcium-dependent but calmodulin-independent protein kinase from soybean. Plant Physiol. 83, 830–837 (1987). , &
- Dissection of mechanisms involved in the regulation of Plasmodium falciparum calcium dependent protein kinase 4 (PfCDPK4). J. Biol. Chem. 284, 15267–15276 (2009). , , &
- Calcium and a calcium-dependent protein kinase regulate gamete formation and mosquito transmission in a malaria parasite. Cell 117, 503–514 (2004). et al.
- The motor complex of Plasmodium falciparum: phosphorylation by a calcium-dependent protein kinase. J. Biol. Chem. 283, 30980–30989 (2008). et al.
- Application of a coupled enzyme assay to characterize nicotinamide riboside kinases. Anal. Biochem. 385, 377–379 (2009). &
- Pseudosubstrate inhibition of CDPK, a protein kinase with a calmodulin-like domain. Biochemistry 33, 7278–7287 (1994). , &
- Intramolecular binding contributes to the activation of CDPK, a protein kinase with a calmodulin-like domain. Biochemistry 35, 12029–12037 (1996). &
- Modulation of calmodulin plasticity in molecular recognition on the basis of X-ray structures. Science 262, 1718–1721 (1993). , &
- Calmodulin structure refined at 1.7 Å resolution. J. Mol. Biol. 228, 1177–1192 (1992). , , &
- Intramolecular activation of a Ca2+-dependent protein kinase is disrupted by insertions in the tether that connects the calmodulin-like domain to the kinase. Biochemistry 39, 4004–4011 (2000). et al.
- A phyloproteomic characterization of in vitro autophosphorylation in calcium-dependent protein kinases. Proteomics 6, 3649–3664 (2006). et al.
- Features of selective kinase inhibitors. Chem. Biol. 12, 621–637 (2005). &
- A unique variation of the ATP binding site makes Toxoplasma gondii calcium-dependent protein kinase 1 a drug target for selective kinase inhibitors. Nat. Struct. Mol. Biol. advance online publication, doi:10.1038/nsmb.1818 (2 May 2010). et al.
- The multifunctional calcium/calmodulin-dependent protein kinase: from form to function. Annu. Rev. Physiol. 57, 417–445 (1995). &
- Dual role of calmodulin in autophosphorylation of multifunctional CaM kinase may underlie decoding of calcium signals. Neuron 12, 943–956 (1994). , , &
- Comparative analysis of the kinomes of three pathogenic trypanosomatids: Leishmania major, Trypanosoma brucei and Trypanosoma cruzi . BMC Genomics 6, 127 (2005). , , &
- Genome-scale protein expression and structural biology of Plasmodium falciparum and related apicomplexan organisms. Mol. Biochem. Parasitol. 151, 100–110 (2007). et al.
- SOLVE and RESOLVE: automated structure solution, density modification and model building. J. Synchrotron Radiat. 11, 49–52 (2004).
- Coot: model-building tools for molecular graphics. Acta Crystallogr. D Biol. Crystallogr. 60, 2126–2132 (2004). &
- NADH-coupled microplate photometric assay for kinetic studies of ATP-hydrolyzing enzymes with low and high specific activities. Anal. Biochem. 321, 266–271 (2003). , &
- Supplementary Text and Figures (2M)
Supplementary Figures 1–4