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Arginine-Enriched Mixed-Charge Domains Provide Cohesion for Nuclear Speckle Condensation
Jamie A Greig1, Tu Anh Nguyen1, Michelle Lee1
1Temasek Life Sciences Laboratory and Department of Biological Sciences, The National University of Singapore, Singapore 117604, Singapore.
Molecular Cell
|February 13, 2020
Summary
Intrinsically disordered mixed-charge domains (MCDs) drive nuclear speckle condensation. Arginine
Area of Science:
- Biochemistry
- Molecular Biology
- Cell Biology
Background:
- Low-complexity protein domains are crucial for biomolecular condensate formation.
- Specific sequence features governing condensate formation and identity are often unclear.
- Nuclear speckles are key sites for mRNA processing and splicing.
Purpose of the Study:
- To investigate the role of intrinsically disordered mixed-charge domains (MCDs) in nuclear speckle condensation.
- To identify sequence determinants controlling MCD-mediated condensate formation and function.
- To link MCD properties to the dynamic material properties of nuclear speckles.
Main Methods:
- Investigated arginine-aspartic acid repeat proteins for condensation and speckle incorporation.
- Utilized synthetic and natural speckle-associated MCDs with substitutions (arginine to lysine).
- Analyzed MCD behavior based on net charge and synergy with RNA recognition motifs.
Main Results:
- Arginine-aspartic acid repeat proteins showed length-dependent condensation and speckle incorporation.
- Replacing arginine with lysine abolished condensation, highlighting arginine's guanidinium ion's role.
- Net charge tuned MCD behavior: negative charge inhibited condensation, while positive charge enhanced it, affecting splicing factors and mRNA export.
Conclusions:
- Identified key sequence determinants of MCD-promoted nuclear speckle condensation.
- Demonstrated arginine's critical role in multivalent contacts for condensate formation.
- Linked MCD-driven material properties of speckles to mRNA processing functions.
Keywords:
biomolecular condensateintrinsically disordered proteinlow-complexity domainmRNA processingmembraneless organellemixed-charge domainnuclear specklephase separationribonucleoprotein (RNP) bodiesMore Related Videos
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