Regulation of the p21-activated kinase-related Dictyostelium myosin I heavy chain kinase by autophosphorylation, acidic phospholipids, and Ca2+-calmodulin.
The Dictyostelium myosin I heavy chain kinase (MIHCK) is a member of the p21-activated kinase family (Lee, S.-F., Egelhoff, T. T., Mahasneh, A., and Côté, G. P. (1996) J. Biol. Chem. 271, 27044-27048). MIHCK incubated with MgATP in the absence of effectors incorporates 1 mol of phosphate/mol, resulting in an approximately 40-fold increase in kinase activity. Sequence analysis of tryptic peptides has identified the major site of phosphorylation as Ser-8. A peptide and a glutathione S-transferase fusion protein containing the Ser-8 phosphorylation site were good substrates for MIHCK, indicating that MIHCK can catalyze its own activation. Guanosine 5'-3-O-(thio)triphosphate (GTPgammaS)-Rac1 stimulates MIHCK autophosphorylation and kinase activity 10-fold. Phosphatidylserine, phosphatidylinositol, and phosphatidylinositol 4,5-bisphosphate, but not phosphatidylcholine or sphingosine, were as effective as GTPgammaS-Rac1 in enhancing MIHCK autophosphorylation and activity. Acidic lipids and GTPgammaS-Rac1 induced the autophosphorylation of a similar set of sites as judged by two-dimensional tryptic peptide maps. It is proposed that GTP-Rac and acidic phospholipids function cooperatively to associate MIHCK with membranes. Ca2+-calmodulin bound MIHCK and inhibited activation by acidic phospholipids but not by GTPgammaS-Rac1. These studies reveal a number of similarities between the regulatory properties of the Dictyostelium and Acanthamoeba MIHCK, suggesting that the signaling pathways that control myosin I are conserved.
Lee
S F
SF
Department of Biochemistry, Queen's University, Kingston, Ontario K7L 3N6, Canada.
Mahasneh
A
A
de la Roche
M
M
Côté
G P
GP
D000818:Animals; D002118:Calcium / Q000494:pharmacology*; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000187:drug effects / Q000378:metabolism*; D002147:Calmodulin / Q000494:pharmacology*; D004023:Dictyostelium / Q000201:enzymology*; D004789:Enzyme Activation; D019204:GTP-Binding Proteins; D020404:Glycerophospholipids / Q000494:pharmacology*; D008954:Models, Biological; D008969:Molecular Sequence Data; D010716:Phosphatidylinositols / Q000494:pharmacology; D010718:Phosphatidylserines / Q000494:pharmacology; D010766:Phosphorylation / Q000187:drug effects; D011485:Protein Binding; D015800:Protozoan Proteins; D020744:rac GTP-Binding Proteins
D002147:Calmodulin; D020404:Glycerophospholipids; D010716:Phosphatidylinositols; D010718:Phosphatidylserines; D015800:Protozoan Proteins; D017871:Calcium-Calmodulin-Dependent Protein Kinases; C033142:myosin-heavy-chain kinase; D019204:GTP-Binding Proteins; D020744:rac GTP-Binding Proteins; D002118:Calcium