Selective Ion Binding and Uptake Shape the Microenvironment of Biomolecular Condensates

Area of Science:

• Biochemistry
• Biophysics
• Cell Biology

Background:

• Biomolecular condensates regulate cellular processes by controlling ion distribution.
• Understanding condensate-ion interactions is crucial for deciphering cellular ion homeostasis.

Purpose of the Study:

• To elucidate the molecular mechanisms governing selective ion binding to biomolecular condensates.
• To quantify and spatially resolve ion interactions with condensate components.

Main Methods:

• Nuclear magnetic resonance (NMR) spectroscopy was employed to study ion binding.
• Model condensate components and various ions were used for quantitative analysis.

Main Results:

• Ion binding to condensates follows the "law of matching water affinities," favoring protein-chaotropic anion and nucleic acid-kosmotropic cation interactions.
• Selective ion uptake into condensates correlates directly with binding affinities, excluding weakly binding ions.
• Ion binding alters the condensate microenvironment, affecting composition, viscosity, and interface potential, impacting biochemical reactions like RNA duplex formation.

Conclusions:

• Condensate-ion interactions are governed by predictable binding rules based on water affinity.
• These interactions play a significant role in cellular bio- and electrochemistry.
• Findings may inform the development of novel therapeutics targeting biomolecular condensates.