Intramolecular conformational changes optimize protein kinase C signaling

Area of Science:

• Biochemistry
• Cell Biology
• Molecular Signaling

Background:

• Enzyme signaling and protein kinase C (PKC) are crucial for maintaining cellular homeostasis.
• PKC is a multidomain signal transducer that responds to second messengers.
• Its domains possess high ligand affinity, necessitating regulatory mechanisms to control activity.

Purpose of the Study:

• To investigate the conformational transitions of protein kinase C (PKC).
• To understand how these transitions tune the enzyme's affinity for diacylglycerol (DAG).
• To elucidate the mechanisms that optimize PKC signaling dynamics.

Main Methods:

• Utilizing fluorescence resonance energy transfer (FRET) reporters in live-cell imaging.
• Observing conformational changes in PKC during cellular signaling.
• Analyzing the role of priming phosphorylations in PKC regulation.

Main Results:

• Newly synthesized PKC initially exposes both diacylglycerol (DAG) sensors (C1A and C1B domains).
• Conformational changes, induced by priming phosphorylations, mask these domains.
• This masking results in the lower-affinity C1B domain becoming the primary DAG binder.

Conclusions:

• Conformational rearrangements in PKC are key to optimizing its signaling dynamic range.
• PKC's regulatory mechanism serves as a model for other multidomain signal transducers.
• Understanding these dynamics is vital for cellular homeostasis and signaling research.