Interplay between intrinsically disordered proteins inside membraneless protein liquid droplets.

Area of Science:

• Biochemistry
• Cell Biology
• Biophysics

Background:

• Intrinsically disordered proteins (IDPs) drive phase separation to form membraneless organelles.
• The impact of interactions between multiple IDPs on droplet dynamics remains poorly understood.

Purpose of the Study:

• To investigate how interactions between different IDPs influence the dynamic behavior and properties of phase-separated protein droplets.
• To explore the recruitment, mobility, fusion, and segregation of IDPs within these droplets.

Main Methods:

• Development of a rapid IDP clustering system to generate protein droplets.
• Examination of diverse interacting IDPs within droplets under crowded conditions.
• Analysis of IDP enrichment, mobility, and droplet fusion dynamics.

Main Results:

• IDP droplets actively recruited other IDPs with significant enrichment (over 100-fold variation).
• Recruited IDPs remained mobile within largely immobile droplets; Ddx4 helicase region showed notable mobility influence.
• Droplets exhibited rapid fusion, sometimes forming heterogeneous structures with segregated subcompartments, dependent on IDP composition and maturation.

Conclusions:

• Interacting IDPs display complex behaviors including recruitment, differential mobility, and fusion within membraneless organelles.
• Specific IDP pairs with distinct residue compositions lead to enhanced segregation upon fusion.
• Findings provide insights into membraneless organelle formation and models for controllable droplet properties.