Farmer PK, Choi JH. Calcium and phospholipid activation of a recombinant calcium-dependent protein kinase (DcCPK1) from carrot (Daucus carota L.).
BIOCHIMICA ET BIOPHYSICA ACTA 1999;
1434:6-17. [PMID:
10556555 DOI:
10.1016/s0167-4838(99)00166-1]
[Citation(s) in RCA: 54] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
A calmodulin-like domain protein kinase (DcCPK1, previously designated CDPK431) cloned from carrot (Daucus carota L.) was expressed at high levels in Escherichia coli and partially purified. Ca(2+)-induced gel mobility shift and (45)Ca(2+) ligand binding assays confirmed that recombinant DcCPK1 binds Ca(2+) through its calmodulin-like domain and undergoes a significant conformational change. Ca(2+) activated the kinase activity of recombinant DcCPK1 (K(0.5)=1.7 microM) up to 20-fold. Ca(2+) combined with certain lipids, including phosphatidic acid, phosphatidylserine and phosphatidylinositol, but not diolein or lysophosphatidylcholine, provided even greater Ca(2+)-dependent protein kinase activity. DcCPK1 phosphorylated casein and histone III-S, and a variety of peptide substrates containing a hydrophobic and a basic residue situated P-5 and P-3 amino acids N-terminal to a Ser or Thr residue. The calmodulin and protein kinase inhibitors, W-7 and staurosporine, inhibited CDPK activity. The similarities between DcCPK1 and mammalian protein kinase C (PKC) in substrate specificity, sensitivity to inhibitors, and activation by Ca(2+) and phospholipid suggest that various CDPK isoforms may be responsible for some PKC-like activities in plant cells.
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