Phosrestide-1, a peptide derived from the Drosophila photoreceptor protein phosrestin I, is a potent substrate for Ca2+/calmodulin-dependent protein kinase II from rat brain.
Multifunctional Ca2+/calmodulin-dependent protein kinase type II (CaMK II) plays a crucial role in mediation of cellular responses to rising cytosolic Ca2+ levels. We find that the novel peptide substrate PGTIEKKRSNAMKKMKSIEQHR serves as a highly potent substrate for CaMK II enzymes purified from both Drosophila and rat. The peptide is derived from a photoreceptor-specific protein, phosrestin I, of the Drosophila compound eye and is designated as phosrestide-1. Using saturating substrate concentrations, the enzymes from both species transfer the gamma-phosphoryl group of ATP to phosrestide-1 at a level three to ten times greater than to the commercially available mammalian-derived CaMK II substrates, autocamtide-3 and syntide-2. This indicates a conservation of substrate preferences for CaMK II derived from distantly related species, a dipteran fly and a mammal. Although phosrestide-1 contains two potential serine residues for CaMK II phosphorylation, we find that only the C-terminal serine is phosphorylated by rat CaMK II. However, removal of the upstream sequence containing the N-terminal serine substantially reduced the potency of phosrestide-1 as a CaMK II substrate to a level comparable to that of syntide-2 or autocamtide-3. We also find that a peptide representing the N-terminal segment of phosrestide-1 does not inhibit either CaMK II. Therefore, the enhanced potency of phosrestide-1 as a CaMK II substrate is likely to be due to a preferred conformation of the peptide induced by the N-terminal segment rather than to a specific binding of the enzymes to the N-terminus of the peptide. To the best of our knowledge, phosrestide-1 is the first CaMK II substrate which is designed based on an invertebrate sequence. The high phosphorylation level of phosrestide-1 by CaMK II of mammalian origin may reflect highly conserved CaMK II signaling cascades between vertebrates and invertebrates.
Kahn
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Department of Biochemistry and Molecular Biology, University of Oklahoma, Oklahoma City 73190, USA.
Kinumi
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Tobin
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Matsumoto
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D000595:Amino Acid Sequence; D000818:Animals; D019390:Arrestins / Q000737:chemistry*; D001665:Binding Sites; D001921:Brain / Q000201:enzymology*; D054732:Calcium-Calmodulin-Dependent Protein Kinase Type 2; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000378:metabolism*; D004330:Drosophila / Q000502:physiology; D019476:Insect Proteins / Q000737:chemistry; D036341:Intercellular Signaling Peptides and Proteins; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000737:chemistry*; D010455:Peptides / Q000378:metabolism; D010750:Phosphoproteins / Q000737:chemistry*; D010766:Phosphorylation; D017956:Photoreceptor Cells, Invertebrate / Q000737:chemistry*; D051381:Rats; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D013379:Substrate Specificity
D019390:Arrestins; D019476:Insect Proteins; D036341:Intercellular Signaling Peptides and Proteins; D010446:Peptide Fragments; D010455:Peptides; D010750:Phosphoproteins; C115604:phosrestide 1; C063391:syntide-2; D054732:Calcium-Calmodulin-Dependent Protein Kinase Type 2; D017871:Calcium-Calmodulin-Dependent Protein Kinases