title: Dissection of mechanisms involved in the regulation of Plasmodium falciparum calcium-dependent protein kinase 4.
abstract: Recent studies have demonstrated that calcium-dependent protein kinases (CDPKs) are used by calcium to regulate a variety of biological processes in the malaria parasite Plasmodium. CDPK4 has emerged as an important enzyme for parasite development, because its gene disruption in rodent parasite Plasmodium berghei causes major defects in sexual differentiation of the parasite ( Billker, O., Dechamps, S., Tewari, R., Wenig, G., Franke-Fayard, B., and Brinkmann, V. (2004) Cell 117, 503-514 ). Despite these findings, it is not very clear how PfCDPK4 or any other PfCDPK is regulated by calcium at the molecular level. We report the biochemical characterization and elucidation of molecular mechanisms involved in the regulation of PfCDPK4. PfCDPK4 was detected on gametocyte periphery, and its activity in the parasite was regulated by phospholipase C. Even though the Junction Domain (JD) of PfCDPK4 shares moderate sequence homology with that of the plant CDPKs, it plays a pivotal role in PfCDPK4 regulation as previously reported for some plant CDPKs. The regions of the J-domain involved in interaction with both the kinase domain and the calmodulin-like domain were mapped. We propose a model for PfCDPK regulation by calcium, which may also prove useful for design of inhibitors against PfCDPK4 and other members of the PfCDPK family.
authors.affiliation: Eukaryotic Gene Expression Laboratory, National Institute of Immunology, New Delhi, India.
authors.forename: Ravikant
authors.initials: R
authors.lastname: Ranjan
authors.forename: Anwar
authors.initials: A
authors.lastname: Ahmed
authors.forename: Samudrala
authors.initials: S
authors.lastname: Gourinath
authors.forename: Pushkar
authors.initials: P
authors.lastname: Sharma
mesh_terms: D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D000818:Animals; D055162:Biocatalysis / Q000187:drug effects; D002118:Calcium / Q000494:pharmacology; D003001:Cloning, Molecular; D004789:Enzyme Activation / Q000187:drug effects; D008018:Life Cycle Stages / Q000187:drug effects; D008954:Models, Biological; D008969:Molecular Sequence Data; D050505:Mutant Proteins / Q000737:chemistry / Q000378:metabolism; D010271:Parasites / Q000187:drug effects / Q000201:enzymology / Q000254:growth & development; D010766:Phosphorylation / Q000187:drug effects; D010769:Phosphothreonine / Q000378:metabolism; D010963:Plasmodium falciparum / Q000187:drug effects / Q000201:enzymology* / Q000254:growth & development; D011494:Protein Kinases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D017434:Protein Structure, Tertiary; D011994:Recombinant Proteins / Q000378:metabolism; D016415:Sequence Alignment; D010738:Type C Phospholipases / Q000378:metabolism; D017871:Calcium-Calmodulin-Dependent Protein Kinases
chemical_list: D002118:Calcium; D050505:Mutant Proteins; D010769:Phosphothreonine; D011494:Protein Kinases; D011994:Recombinant Proteins; D010738:Type C Phospholipases; D017871:Calcium-Calmodulin-Dependent Protein Kinases