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This content will become publicly available on November 12, 2016

Title: Protein kinase A catalytic subunit primed for action: Time-lapse crystallography of Michaelis complex formation

The catalytic subunit of the cyclic AMP-dependent protein kinase A (PKAc) catalyzes the transfer of the γ-phosphate of bound Mg2ATP to a serine or threonine residue of a protein substrate. Here, time-lapse X-ray crystallography was used to capture a series of complexes of PKAc with an oligopeptide substrate and unreacted Mg2ATP, including the Michaelis complex, that reveal important geometric rearrangements in and near the active site preceding the phosphoryl transfer reaction. Contrary to the prevailing view, Mg2+ binds first to the M1 site as a complex with ATP and is followed by Mg2+ binding to the M2 site. Furthermore, the target serine hydroxyl of the peptide substrate rotates away from the active site toward the bulk solvent, which breaks the hydrogen bond with D166. In conclusion, the serine hydroxyl of the substrate rotates back toward D166 to form the Michaelis complex with the active site primed for phosphoryl transfer.
Authors:
 [1] ;  [1] ;  [1] ;  [1] ;  [1] ;  [1]
  1. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Publication Date:
OSTI Identifier:
1235817
Grant/Contract Number:
AC05-00OR22725
Type:
Accepted Manuscript
Journal Name:
Structure
Additional Journal Information:
Journal Volume: 23; Journal Issue: 12; Journal ID: ISSN 0969-2126
Publisher:
Elsevier
Research Org:
Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)
Sponsoring Org:
USDOE Office of Science (SC)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY