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Assaying Protein Kinase Activity with Radiolabeled ATP
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Differential AMP-activated Protein Kinase (AMPK) Recognition Mechanism of Ca2+/Calmodulin-dependent Protein Kinase

Yuya Fujiwara1, Yoshinori Kawaguchi1, Tomohito Fujimoto2

  • 1From the Division of Medical Bioengineering, Graduate School of Natural Science and Technology, Okayama University, Okayama 700-8530, Japan and.

The Journal of Biological Chemistry
|May 7, 2016
PubMed

Insights

Calcium/calmodulin-dependent protein kinase kinase beta (CaMKKβ) activates AMP-activated protein kinase (AMPK). Subdomain VIII of CaMKK and specific amino acids (Leu358 in CaMKKβ/Ile322 in CaMKKα) are crucial for CaMKKβ

Area of Science:

  • Biochemistry
  • Molecular Biology
  • Enzymology

Background:

  • Calcium/calmodulin-dependent protein kinase kinase beta (CaMKKβ) is a key activator of AMP-activated protein kinase (AMPK).
  • CaMKKβ exhibits higher in vitro catalytic efficiency for AMPK phosphorylation compared to CaMKKα.
  • The substrate specificity of CaMKK isoforms towards AMPK and CaMKIα requires further elucidation.

Purpose of the Study:

  • To investigate the molecular determinants underlying the substrate discrimination between CaMKKβ and CaMKKα for AMPK.
  • To identify specific regions and residues within CaMKK responsible for differential AMPK recognition.

Main Methods:

  • Construction and activity assays of CaMKKα/CaMKKβ chimera mutants.
  • Site-directed mutagenesis to pinpoint critical amino acid residues.
  • In vitro kinase assays measuring phosphorylation of AMPK and CaMKIα.

Main Results:

  • Subdomain VIII of CaMKK plays a significant role in distinguishing AMPK as a substrate.
  • Specific residues, Leu358 in CaMKKβ and Ile322 in CaMKKα, contribute to the distinct recognition of AMPK.
  • These identified residues do not appear to affect the recognition of CaMKIα.

Conclusions:

  • CaMKK subdomain VIII and specific amino acid residues mediate the selective activation of AMPK by CaMKKβ.
  • Understanding these molecular mechanisms provides insights into the regulation of AMPK signaling pathways.
  • This research highlights the structural basis for kinase-substrate specificity in the CaMKK-AMPK interaction.
Keywords:
AMP-activated kinase (AMPK)Ca2+/calmodulin-dependent protein kinase (CaMK)CaMKICaMKKcalmodulin (CaM)phosphorylationsubstrate recognitionsubstrate specificity

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