Retinoic Acid Binding Leads to CRABP2 Rigidification and Dimerization.

Area of Science:

• Molecular Biology
• Structural Biology
• Biochemistry

Background:

• Cellular retinoic acid-binding protein 2 (CRABP2) facilitates the transport of all-trans retinoic acid (atRA) to retinoic acid receptors (RARs).
• Understanding the structural dynamics of CRABP2 upon atRA binding is crucial for elucidating its cellular functions and interactions with downstream partners.

Purpose of the Study:

• To investigate the molecular mechanisms underlying atRA binding to CRABP2.
• To explore how atRA binding influences CRABP2's structure, dynamics, and interaction interfaces.

Main Methods:

• Nuclear magnetic resonance (NMR) spectroscopy was employed to study the atRA:CRABP2 interaction.
• Analysis focused on changes in protein dynamics and structural conformation upon ligand binding.

Main Results:

• atRA binding significantly suppresses the intermediate- and fast-time scale dynamics of CRABP2.
• CRABP2 rigidification upon atRA binding stabilizes a homodimerization interface involving specific helix and loop regions.
• This rigidification impacts CRABP2's nuclear localization signal and RAR-binding motif.

Conclusions:

• The loss of conformational entropy due to CRABP2 rigidification upon atRA binding is a key determinant of its diverse cellular roles.
• The study provides structural insights into CRABP2's function in regulating gene transcription via atRA signaling.