Dataset Information

Biophysical characterization of the calmodulin-like domain of Plasmodium falciparum calcium dependent protein kinase 3.

ABSTRACT: Calcium dependent protein kinases are unique to plants and certain parasites and comprise an N-terminal segment and a kinase domain that is regulated by a C-terminal calcium binding domain. Since the proteins are not found in man they are potential drug targets. We have characterized the calcium binding lobes of the regulatory domain of calcium dependent protein kinase 3 from the malaria parasite Plasmodium falciparum. Despite being structurally similar, the two lobes differ in several other regards. While the monomeric N-terminal lobe changes its structure in response to calcium binding and shows global dynamics on the sub-millisecond time-scale both in its apo and calcium bound states, the C-terminal lobe could not be prepared calcium-free and forms dimers in solution. If our results can be generalized to the full-length protein, they suggest that the C-terminal lobe is calcium bound even at basal levels and that activation is caused by the structural reorganization associated with binding of a single calcium ion to the N-terminal lobe.

SUBMITTER: Andresen C

PROVIDER: S-EPMC5528832 | biostudies-literature | 2017

REPOSITORIES: biostudies-literature

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Biophysical characterization of the calmodulin-like domain of Plasmodium falciparum calcium dependent protein kinase 3.

Andresen Cecilia C Niklasson Markus M Cassman Eklöf Sofie S Wallner Björn B Lundström Patrik P

PloS one 20170726 7

Calcium dependent protein kinases are unique to plants and certain parasites and comprise an N-terminal segment and a kinase domain that is regulated by a C-terminal calcium binding domain. Since the proteins are not found in man they are potential drug targets. We have characterized the calcium binding lobes of the regulatory domain of calcium dependent protein kinase 3 from the malaria parasite Plasmodium falciparum. Despite being structurally similar, the two lobes differ in several other reg ...[more]

PMID: 28746405

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Project description:We used a sensitization approach that involves replacement of the gatekeeper residue in a protein kinase with one with a different side chain. The activity of the enzyme with a bulky gatekeeper residue, such as methionine, cannot be inhibited using bumped kinase inhibitors (BKIs). Here, we have used this approach to study Plasmodium falciparum calcium-dependent protein kinase 1 (PfCDPK1). The methionine gatekeeper substitution, T145M, although it led to a 47% reduction in transphosphorylation, was successfully introduced into the CDPK1 locus using clustered regularly interspaced short palindromic repeat (CRISPR)/Cas9. As methionine is a bulky residue, BKI 1294 had a 10-fold-greater effect in vitro on the wild-type enzyme than on the methionine mutant. However, in contrast to in vitro data with recombinant enzymes, BKI 1294 had a slightly greater inhibition of the growth of CDPK1 T145M parasites than the wild type. Moreover, the CDPK1 T145M parasites were more sensitive to the action of compound 2 (C2), a specific inhibitor of protein kinase G (PKG). These results suggest that a reduction in the activity of CDPK1 due to methionine substitution at the gatekeeper position is compensated through the direct action of PKG or of another kinase under the regulation of PKG. The transcript levels of CDPK5 and CDPK6 were significantly upregulated in the CDPK1 T145M parasites. The increase in CDPK6 or some other kinase may compensate for decrease in CDPK1 activity during invasion. This study suggests that targeting two kinases may be more effective in chemotherapy to treat malaria so as not to select for mutations in one of the enzymes.ImportanceProtein kinases of Plasmodium falciparum are being actively pursued as drug targets to treat malaria. However, compensatory mechanisms may reverse the drug activity against a kinase. In this study, we show that replacement of the wild-type threonine gatekeeper residue with methionine reduces the transphosphorylation activity of CDPK1. Mutant parasites with methionine gatekeeper residue compensate the reduced activity of CDPK1 through the action of PKG possibly by upregulation of CDPK6 or some other kinase. This study highlights that targeting one enzyme may lead to changes in transcript expression of other kinases that compensate for its function and may select for mutants that are less dependent on the target enzyme activity. Thus, inhibiting two kinases is a better strategy to protect the antimalarial activity of each, similar to artemisinin combination therapy or malarone (atovaquone and proguanil).

Dataset Information

Biophysical characterization of the calmodulin-like domain of Plasmodium falciparum calcium dependent protein kinase 3.

Publications

Biophysical characterization of the calmodulin-like domain of Plasmodium falciparum calcium dependent protein kinase 3.

Similar Datasets

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