PKA: a portrait of protein kinase dynamics

Area of Science:

• Molecular biology
• Biochemistry
• Cellular signaling

Background:

• Protein kinases, particularly cAMP-dependent protein kinase (PKA), are central to eukaryotic cell signaling networks.
• PKA's catalytic subunit exemplifies substrate recognition, inhibition, and catalytic mechanisms.
• Understanding PKA signaling requires examining its catalytic and regulatory subunits, as well as A kinase anchoring proteins (AKAPs).

Purpose of the Study:

• To summarize conformational states of PKA's catalytic subunit involved in its catalytic cycle.
• To elucidate the molecular events and critical residues driving PKA catalysis.
• To explore the dynamic properties and interactions of PKA components using various biophysical techniques.

Main Methods:

• X-ray crystallography and NMR to determine high-resolution structures.
• Fluorescent tools to probe protein dynamics.
• Hydrogen/deuterium exchange coupled with mass spectrometry (HDX-MS) to study protein interactions and dynamics.
• Development of a novel recombinantly expressed PKA reporter for in vivo activity monitoring.

Main Results:

• Detailed structural insights into PKA's catalytic cycle and the roles of specific residues.
• Characterization of PKA's dynamic behavior and interactions in solution.
• Demonstration of AKAPs' role in localizing PKA via regulatory subunit docking.
• Successful development and application of a new PKA activity reporter for living cells.

Conclusions:

• The entire PKA molecule, including catalytic and regulatory subunits and AKAPs, is essential for integrated cellular signaling.
• Structural and dynamic studies provide a comprehensive understanding of PKA's catalytic mechanisms and regulatory strategies.
• The new PKA reporter enables real-time monitoring of kinase activity in cellular contexts, advancing signaling research.