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Structural characterization of Ca 2+ /CaM in complex with the phosphorylase kinase PhK5 peptide
Author(s) -
Cook Atlanta G.,
Johnson Louise N.,
McDonnell James M.
Publication year - 2005
Publication title -
the febs journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.981
H-Index - 204
eISSN - 1742-4658
pISSN - 1742-464X
DOI - 10.1111/j.1742-4658.2005.04591.x
Subject(s) - phosphorylase kinase , calmodulin , chemistry , protein subunit , peptide , kinase , arginine kinase , myosin light chain kinase , biochemistry , biophysics , protein kinase a , glycogen phosphorylase , enzyme , stereochemistry , crystallography , biology , myosin , arginine , amino acid , gene
Phosphorylase kinase (PhK) is a large hexadecameric enzyme consisting of four copies of four subunits: (αβγδ) 4 . An intrinsic calmodulin (CaM, the δ subunit) binds directly to the γ protein kinase chain. The interaction site of CaM on γ has been localized to a C‐terminal extension of the kinase domain. Two 25‐mer peptides derived from this region, PhK5 and PhK13, were identified previously as potential CaM‐binding sites. Complex formation between Ca 2+ /CaM with these two peptides was characterized using analytical gel filtration and NMR methods. NMR chemical shift perturbation studies showed that while PhK5 forms a robust complex with Ca 2+ /CaM, no interactions with PhK13 were observed. 15 N relaxation characteristics of Ca 2+ /CaM and Ca 2+ /CaM/PhK5 complexes were compared with the experimentally determined structures of several Ca 2+ /CaM/peptide complexes. Good fits were observed between Ca 2+ /CaM/PhK5 and three structures: Ca 2+ /CaM complexes with peptides from endothelial nitric oxide synthase, with smooth muscle myosin light chain kinase and CaM kinase I. We conclude that the PhK5 site is likely to have a direct role in Ca 2+ ‐regulated control of PhK activity through the formation of a classical ‘compact’ CaM complex.