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In vitro reconstitution of interactions in the CARD9 signalosome
Jin Hee Park1, Jae Young Choi1, Mir Faisal Mustafa1
1School of Chemistry and Biochemistry and Graduate School of Biochemistry, Yeungnam University, Gyeongsangnam 38541, Republic of Korea.
Insights
The CARD9 signalosome, crucial for innate immunity, was structurally and biochemically characterized. Researchers reconstituted CARD9-BCL10 complexes in vitro, revealing key interactions for signalosome assembly.
Area of Science:
- Immunology
- Molecular Biology
- Structural Biology
Background:
- The caspase-associated recruitment domain (CARD)‑containing protein 9 (CARD9) signalosome, comprising CARD9, B‑cell CLL/lymphoma 10 (BCL10), and mucosa‑associated lymphoid tissue lymphoma translocation protein 1 (MALT1), plays vital roles in myeloid cell activation via nuclear factor‑κB pathways during innate immunity.
- BCL10 acts as an adaptor protein, mediating interactions within the CARD9 signalosome through CARD-CARD interactions with CARD9 and interactions with MALT1.
- Despite its importance, the structural and biochemical characteristics of the CARD9 signalosome remain largely unelucidated.
Purpose of the Study:
- To elucidate the structural and biochemical characteristics of the CARD9 signalosome.
- To investigate the interaction mechanisms between CARD9 and BCL10 within the signalosome.
- To provide a deeper understanding of CARD9 signalosome assembly.
Main Methods:
- Purification and biochemical characterization of CARD9 and BCL10 CARDs.
- In vitro reconstitution of CARD9-BCL10 complexes under specific conditions (low salt and pH).
- Structural modeling to propose a mechanism for CARD9-BCL10 interactions.
Main Results:
- Successful purification and characterization of CARD9 and BCL10 CARDs.
- Reconstitution of CARD9-BCL10 complexes in vitro, indicating their ability to form stable interactions.
- Development of a structural model elucidating the interaction scheme between CARD9 and BCL10.
Conclusions:
- The study successfully characterized key components of the CARD9 signalosome, providing insights into their biochemical properties.
- The in vitro reconstitution and structural modeling offer a foundational understanding of CARD9-BCL10 interactions.
- This work contributes to a clearer picture of CARD9 signalosome assembly mechanisms, essential for innate immune responses.
Abstract:
The caspase-associated recruitment domain (CARD)‑containing protein 9 (CARD9) signalosome is composed of CARD9, B‑cell CLL/lymphoma 10 (BCL10) and mucosa‑associated lymphoid tissue lymphoma translocation protein 1 (MALT1). The CARD9 signalosome has been reported to exert critical functions in the immunoreceptor tyrosine‑based activation motif‑coupled receptor‑mediated activation of myeloid cells, through nuclear factor‑κB pathways during innate immunity processes. During CARD9 signalosome assembly, BCL10 has been revealed to function as an adaptor protein and to interact with CARD9 via CARD‑CARD interactions; BCL10 also interacts with MALT1 via its C‑terminal Ser/Thr‑rich region and the first immunoglobulin domain of MALT1. The CARD9 signalosome is implicated in critical biological processes; however, its structural and biochemical characteristics have yet to be elucidated. In the present study, CARD9 and BCL10 CARDs were successfully purified and characterized, and their biochemical properties were investigated. In addition, CARD9‑BCL10 complexes were reconstituted in vitro under low salt and pH conditions. Furthermore, based on structural modeling data, a scheme was proposed to describe the interactions between CARD9 and BCL10. This provides a further understanding of the mechanism of how the CARD9 signalosome may be assembled.