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Updated: Sep 26, 2025
In Situ Detection of Ribonucleoprotein Complex Assembly in the C. elegans Germline using Proximity Ligation Assay
Published on: May 5, 2020
Low complexity RGG-motif sequence is required for Processing body (P-body) disassembly
Raju Roy1, Gitartha Das1, Ishwarya Achappa Kuttanda1
1Department of Biochemistry, Indian Institute of Science, Bangalore, 560012, India.
Abstract:
P-bodies are conserved mRNP complexes that are implicated in determining mRNA fate by affecting translation and mRNA decay. In this report, we identify RGG-motif containing translation repressor protein Sbp1 as a disassembly factor of P-bodies since disassembly of P-bodies is defective in Δsbp1. RGG-motif is necessary and sufficient to rescue the PB disassembly defect in Δsbp1. Binding studies using purified proteins revealed that Sbp1 physically interacts with Edc3 and Sbp1-Edc3 interaction competes with Edc3-Edc3 interaction. Purified Edc3 forms assemblies, promoted by the presence of RNA and NADH and the addition of purified Sbp1, but not the RGG-deletion mutant, leads to significantly decreased Edc3 assemblies. We further note that the aggregates of human EWSR1 protein, implicated in neurodegeneration, are more persistent in the absence of Sbp1 and overexpression of EWSR1 in Δsbp1 leads to a growth defect. Taken together, our observations suggest a role of Sbp1 in disassembly, which could apply to disease-relevant heterologous protein-aggregates.
Insights
The protein Sbp1 is identified as a key factor in the disassembly of processing bodies (P-bodies). Its absence impairs P-body disassembly and affects the aggregation of disease-related proteins.
Area of Science:
- Cell Biology
- Molecular Biology
- Biochemistry
Background:
- Processing bodies (P-bodies) are crucial cellular structures regulating mRNA fate, influencing translation and decay.
- The precise mechanisms governing P-body dynamics, particularly disassembly, remain incompletely understood.
- Identifying factors that control P-body assembly and disassembly is essential for understanding gene expression regulation.
Purpose of the Study:
- To identify novel factors involved in P-body disassembly.
- To elucidate the molecular mechanism by which Sbp1 influences P-body dynamics.
- To investigate the potential role of Sbp1 in the regulation of disease-associated protein aggregates.
Main Methods:
- Genetic analysis of P-body disassembly in yeast mutants lacking Sbp1 (Δsbp1).
- Biochemical assays using purified proteins to study Sbp1-Edc3 interactions.
- In vitro assembly assays with purified Edc3, RNA, NADH, and Sbp1 or its mutants.
- Analysis of human EWSR1 protein aggregation in yeast models.
Main Results:
- Sbp1 acts as a P-body disassembly factor, with disassembly defective in Δsbp1 cells.
- The RGG-motif of Sbp1 is essential for its function in P-body disassembly.
- Sbp1 directly interacts with Edc3, competing with Edc3 self-interaction and inhibiting Edc3 assembly.
- Absence of Sbp1 leads to persistent aggregates of human EWSR1 protein, causing growth defects upon EWSR1 overexpression.
Conclusions:
- Sbp1 is a critical regulator of P-body disassembly, functioning through interaction with Edc3.
- Sbp1's role in protein aggregate management extends to disease-relevant proteins like EWSR1.
- These findings highlight Sbp1 as a potential target for modulating P-body dynamics and protein aggregation in disease contexts.
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