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Updated: Aug 7, 2026
Transgenic Rodent Assay for Quantifying Male Germ Cell Mutant Frequency
Published on: August 6, 2014
Details of Toll-like receptor:adapter interaction revealed by germ-line mutagenesis
Zhengfan Jiang1, Philippe Georgel, Chenglong Li
1Department of Immunology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, USA.
Abstract:
The immunovariant N-ethyl-N-nitrosourea-induced mutations Pococurante (Poc) and Lackadaisical were found to alter MyD88, creating striking receptor-selective effects. Poc, in particular, prevented sensing of all MyD88-dependent Toll-like receptor (TLR) ligands except diacyl lipopeptides. Furthermore, Poc-site and classical BB loop mutations caused equivalent phenotypes when engrafted into any TLR/IL-1 receptor/resistance (TIR) domain. These observations, complemented by data from docking studies and site-directed mutagenesis, revealed that BB loops and Poc sites interact homotypically across the receptor:adapter signaling interface, whereas the C-terminal alpha(E)-helices support adapter:adapter and receptor:receptor oligomerization. We have thus defined the TIR domain surface that mediates association between TLRs and MyD88 and the surface required for MyD88 or TLR oligomerization. Moreover, MyD88 engages individual TLRs differently, suggesting the feasibility of selective pharmacologic TIR domain receptor blockade.
Insights
Mutations in MyD88, like Pococurante (Poc), alter Toll-like receptor (TLR) signaling selectivity. Understanding these TIR domain interactions reveals potential for targeted TLR blockade therapies.
Area of Science:
- Immunology
- Molecular Biology
- Structural Biology
Background:
- Myeloid differentiation factor 88 (MyD88) is a crucial adaptor protein in Toll-like receptor (TLR) and IL-1 receptor signaling pathways.
- Understanding the molecular interfaces governing TLR-MyD88 interactions and receptor/adaptor oligomerization is key to modulating innate immune responses.
Purpose of the Study:
- To elucidate the structural basis of MyD88-dependent TLR signaling specificity.
- To define the molecular surfaces involved in TLR-MyD88 complex formation and receptor/adaptor oligomerization.
- To explore the potential for selective pharmacologic blockade of TIR domain interactions.
Main Methods:
- Analysis of immunovariant mutations (Pococurante and Lackadaisical) in MyD88.
- Site-directed mutagenesis and domain-swapping experiments within the TLR/IL-1 receptor/resistance (TIR) domain.
- Molecular docking studies to predict interaction interfaces.
Main Results:
- Specific mutations (Pococurante) conferred receptor-selective effects, altering MyD88's ability to sense various TLR ligands.
- Poc-site and BB loop mutations within the TIR domain induced similar phenotypes, indicating their role in receptor:adapter interactions.
- Defined distinct molecular surfaces: BB loops/Poc sites for receptor:adapter interaction, and C-terminal alpha(E)-helices for adapter:adapter and receptor:receptor oligomerization.
Conclusions:
- The study precisely maps the TIR domain surfaces mediating TLR-MyD88 association and receptor/adaptor oligomerization.
- Demonstrated differential engagement of MyD88 by individual TLRs.
- Provides a structural basis for developing selective pharmacologic inhibitors targeting specific TIR domain interactions.
