Serine/threonine phosphorylation of calmodulin modulates its interaction with the binding domains of target enzymes.
The interaction of serine/threonine-phosphorylated calmodulin with synthetic peptides corresponding to the calmodulin-binding domains of six enzymes has been studied by fluorescence spectroscopy. For five peptides, the dissociation constant of the calmodulin-peptide complex (K(d)) increased when calmodulin was phosphorylated. An increase of more than one order of magnitude was observed with peptides derived from smooth-muscle myosin light-chain kinase and cAMP phosphodiesterase. In contrast, only a slight increase in K(d) was noted with two peptides derived from the plasma membrane Ca(2+)-ATPase and for the peptide derived from nitric oxide synthase. No significant change in affinity was detected with the peptide derived from calcineurin. In contrast, a decrease in the dissociation constant was observed with the peptide derived from the Ca(2+)-calmodulin dependent kinase II. Phosphorylation also affected the peptide-calmodulin binding stoichiometry: a decrease from two to one binding sites was observed with the peptides derived from myosin light-chain kinase and phosphodiesterase.
Leclerc
E
E
Department of Biochemistry III, ETH-Zürich, Universitätsstrasse 16, 8092 Zürich, Switzerland.
Corti
C
C
Schmid
H
H
Vetter
S
S
James
P
P
Carafoli
E
E
D015105:3',5'-Cyclic-AMP Phosphodiesterases / Q000378:metabolism; D000595:Amino Acid Sequence; D001665:Binding Sites; D000252:Calcium-Transporting ATPases / Q000378:metabolism; D002147:Calmodulin / Q000378:metabolism*; D002148:Calmodulin-Binding Proteins / Q000378:metabolism*; D047390:Casein Kinase II; D003619:Dansyl Compounds; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009219:Myosin-Light-Chain Kinase / Q000378:metabolism; D010446:Peptide Fragments / Q000378:metabolism; D010750:Phosphoproteins / Q000378:metabolism*; D010766:Phosphorylation; D011485:Protein Binding; D011499:Protein Processing, Post-Translational; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D020836:Protein Structure, Quaternary; D012694:Serine / Q000378:metabolism; D013912:Threonine / Q000378:metabolism
D002147:Calmodulin; D002148:Calmodulin-Binding Proteins; D003619:Dansyl Compounds; D010446:Peptide Fragments; D010750:Phosphoproteins; D013912:Threonine; D012694:Serine; D047390:Casein Kinase II; D017346:Protein Serine-Threonine Kinases; D009219:Myosin-Light-Chain Kinase; D015105:3',5'-Cyclic-AMP Phosphodiesterases; D000252:Calcium-Transporting ATPases