Cationic Amino Acid Identity and Net Charge Influence Condensate Properties in E. coli
Aaron K Kidane1,2, Jacob R Rosenfeld1, Jake D Johnston2,3
1Department of Chemical Engineering, Columbia University, New York, New York 10027, United States.
Biomacromolecules
|September 3, 2025
Summary
The identity of specific amino acids, like arginine, significantly impacts how biomolecular condensates form and behave. This primary sequence information is crucial for understanding condensate dynamics beyond just charge and disorder.
Area of Science:
- Biochemistry
- Molecular Biology
- Cell Biology
Background:
- Biomolecular condensates (BMCs) are essential for organizing cellular functions, including RNA metabolism and stress responses.
- The precise mechanisms by which primary amino acid sequences influence BMC formation and dynamics are not fully understood.
Purpose of the Study:
- To investigate the role of cationic amino acid identity in shaping the properties of protein-RNA coacervates.
- To determine how arginine, compared to other cationic amino acids, affects condensate formation and dynamics.
Main Methods:
- Utilized engineered recombinant proteins to create protein-RNA coacervates.
- Assessed phase boundaries, salt resistance, condensate formation in vivo (E. coli), and protein mobility in vitro and in cells.
Main Results:
- Phase boundaries of coacervates are influenced by both amino acid identity and protein net charge.
- Arginine promotes higher salt resistance and enhanced condensate formation compared to other cationic amino acids with identical charge at physiological pH.
- Arginine incorporation leads to reduced protein mobility within condensates, both in vitro and in cellular environments.
Conclusions:
- Beyond electrostatics and intrinsic disorder, the primary amino acid sequence and side chain composition are critical determinants of biomolecular condensate dynamics.
- Arginine's specific properties play a significant role in modulating the formation, stability, and internal dynamics of protein-RNA coacervates.
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