The CaMKII holoenzyme structure in activation-competent conformations

Nat Commun. 2017 Jun 7;8:15742. doi: 10.1038/ncomms15742.

Abstract

The Ca2+/calmodulin-dependent protein kinase II (CaMKII) assembles into large 12-meric holoenzymes, which is thought to enable regulatory processes required for synaptic plasticity underlying learning, memory and cognition. Here we used single particle electron microscopy (EM) to determine a pseudoatomic model of the CaMKIIα holoenzyme in an extended and activation-competent conformation. The holoenzyme is organized by a rigid central hub complex, while positioning of the kinase domains is highly flexible, revealing dynamic holoenzymes ranging from 15-35 nm in diameter. While most kinase domains are ordered independently, ∼20% appear to form dimers and <3% are consistent with a compact conformation. An additional level of plasticity is revealed by a small fraction of bona-fide 14-mers (<4%) that may enable subunit exchange. Biochemical and cellular FRET studies confirm that the extended state of CaMKIIα resolved by EM is the predominant form of the holoenzyme, even under molecular crowding conditions.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Calcium-Calmodulin-Dependent Protein Kinase Type 2 / chemistry*
  • Calcium-Calmodulin-Dependent Protein Kinase Type 2 / genetics
  • Calcium-Calmodulin-Dependent Protein Kinase Type 2 / metabolism*
  • Enzyme Activation
  • Fluorescence Resonance Energy Transfer
  • Humans
  • Microscopy, Electron / methods
  • Models, Molecular
  • Mutation
  • Phosphorylation
  • Protein Conformation
  • Protein Domains
  • Protein Multimerization
  • Rats

Substances

  • CAMK2A protein, human
  • Calcium-Calmodulin-Dependent Protein Kinase Type 2