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The crystal structure of a phosphorylase kinase peptide substrate complex: kinase substrate recognition
Author(s) -
Lowe E.D.,
Noble M.E.M.,
Skamnaki V.T.,
Oikonomakos N.G.,
Owen D.J.,
Johnson L.N.
Publication year - 1997
Publication title -
the embo journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 7.484
H-Index - 392
eISSN - 1460-2075
pISSN - 0261-4189
DOI - 10.1093/emboj/16.22.6646
Subject(s) - biology , substrate (aquarium) , kinase , substrate specificity , biochemistry , glycogen phosphorylase , peptide , enzyme , microbiology and biotechnology , ecology
The structure of a truncated form of the γ‐subunit of phosphorylase kinase (PHKγ t ) has been solved in a ternary complex with a non‐hydrolysable ATP analogue (adenylyl imidodiphosphate, AMPPNP) and a heptapeptide substrate related in sequence to both the natural substrate and to the optimal peptide substrate. Kinetic characterization of the phosphotransfer reaction confirms the peptide to be a good substrate, and the structure allows identification of key features responsible for its high affinity. Unexpectedly, the substrate peptide forms a short anti‐parallel β‐sheet with the kinase activation segment, the region which in other kinases plays an important role in regulation of enzyme activity. This anchoring of the main chain of the substrate peptide at a fixed distance from the γ‐phosphate of ATP explains the selectivity of PHK for serine/threonine over tyrosine as a substrate. The catalytic core of PHK exists as a dimer in crystals of the ternary complex, and the relevance of this phenomenon to its in vivo recognition of dimeric glycogen phosphorylase b is considered.