Structural biology turned on its head.

Area of Science:

• Molecular Biology
• Biochemistry
• Structural Biology

Background:

• Intrinsically disordered proteins (IDPs) play crucial roles in cellular regulation.
• The protein 4E-BP2 is involved in regulating translation initiation.
• Understanding the structural changes and functional consequences of post-translational modifications like phosphorylation is vital.

Purpose of the Study:

• To investigate the structural and functional impact of phosphorylation on eukaryotic translation initiation factor 4E-binding protein 2 (4E-BP2).
• To elucidate the mechanism by which phosphorylation regulates the interaction between 4E-BP2 and eukaryotic translation initiation factor 4E (eIF4E).

Main Methods:

• Nuclear Magnetic Resonance (NMR) spectroscopy was employed to determine structural changes.
• Isothermal Titration Calorimetry (ITC) was used to assess binding affinities and thermodynamics.
• Combined application of NMR and ITC to study protein-protein interactions.

Main Results:

• Phosphorylation of 4E-BP2 induces a transition from an intrinsically disordered state to a stable three-dimensional folded structure.
• This phosphorylation-induced folding leads to the inhibition of 4E-BP2 binding to eIF4E.
• The study demonstrates an inverse structure-function paradigm where folding, rather than disorder, mediates regulatory inhibition.

Conclusions:

• Phosphorylation-mediated folding of 4E-BP2 is a key regulatory mechanism controlling its interaction with eIF4E.
• This mechanism highlights a novel mode of protein function regulation, challenging classical structure-function paradigms.
• The findings provide insights into the dynamic regulation of translation initiation by IDPs.