Related Experiment Videos
Tumor necrosis factor receptor 1 is an ATPase regulated by silencer of death domain
1Gamete Biology Section, Laboratory of Reproductive and Developmental Toxicology, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, North Carolina 27709, USA.
Abstract:
Self-aggregation of tumor necrosis factor receptor type 1 (TNFR1) induces spontaneous downstream signaling and results in cell death. It has been suggested that silencer of death domain (SODD) binds TNFR1 monomers to prevent self-aggregation. We found that SODD binds through its BAG domain to the ATPase domain of Hsp70. We also determined that SODD binds through its BAG domain to TNFR1. ATP, but not nonhydrolyzable ATP-gamma S, regulates the SODD binding by Hsp70 or TNFR1. ATP binding by TNFR1 was abolished when a point mutation was introduced into a phosphate-binding loop motif characteristic of ATP-binding proteins, suggesting that TNFR1 functions as an ATPase. Furthermore, TNFR1 was present in aggregates in ATP-depleted cells and SODD disassembled aggregates in vitro only in the presence of ATP. These data suggest that SODD functions as a cofactor analogous to the nucleotide exchange factor BAG-1, which modulates the ATPase cycle of Hsp70 proteins. We propose a new model in which a nucleotide-dependent conformational change in TNFR1 has a key role in regulating TNF signaling.
Insights
Silencer of death domain (SODD) regulates tumor necrosis factor receptor type 1 (TNFR1) aggregation and signaling. SODD acts as a cofactor, modulating TNFR1
Area of Science:
- Cellular Biology
- Molecular Biology
- Biochemistry
Background:
- Self-aggregation of tumor necrosis factor receptor type 1 (TNFR1) triggers cell death pathways.
- Silencer of death domain (SODD) is hypothesized to prevent TNFR1 self-aggregation.
Purpose of the Study:
- To elucidate the molecular mechanism by which SODD regulates TNFR1 aggregation and signaling.
- To investigate the role of ATP in TNFR1-SODD interactions and TNFR1 function.
Main Methods:
- Co-immunoprecipitation assays to determine protein-protein interactions.
- ATPase assays and point mutation analysis to characterize TNFR1's enzymatic activity.
- In vitro aggregation and disassembly assays.
Main Results:
- SODD binds to both Hsp70 and TNFR1 via its BAG domain.
- ATP binding regulates SODD's interaction with Hsp70 and TNFR1, indicating TNFR1 possesses ATPase activity.
- TNFR1 forms aggregates in ATP-depleted conditions, and SODD disassembles these aggregates in an ATP-dependent manner.
Conclusions:
- SODD functions as an ATP-dependent cofactor, similar to BAG-1, modulating TNFR1's ATPase cycle.
- A nucleotide-dependent conformational change in TNFR1 is proposed to be critical for regulating TNF signaling pathways.