Structure-Activity Relationship in TLR4 Mutations: Atomistic Molecular Dynamics Simulations and Residue Interaction...

Area of Science:

• Immunology
• Structural Biology
• Computational Biology

Background:

• Toll-like receptor 4 (TLR4) is crucial for innate immunity, initiating signaling upon detecting danger signals or bacterial components.
• TLR4 function relies on a stable hexamer complex, essential for cytoplasmic domain dimerization.
• Specific polymorphisms, D299G and T399I, may compromise TLR4 complex stability and signaling.

Purpose of the Study:

• To investigate the dynamic behavior and structural consequences of TLR4 polymorphisms using computational methods.
• To elucidate the molecular mechanisms underlying compromised TLR4 signaling in mutated variants.

Main Methods:

• Molecular dynamics simulations (MDS) were employed to analyze the structural dynamics of wild-type and mutated TLR4 complexes.
• Principal component analysis (PCA) was used to identify key motions and conformational changes.
• Residue interaction network (RIN) analysis was performed to map signaling propagation pathways.

Main Results:

• Mutated TLR4 complexes exhibited reduced cohesion, altered secondary structures, and anomalous dynamics.
• PCA revealed distinct low-frequency motions in mutated complexes, correlating with altered function.
• RIN analysis indicated that mutations may lead to aberrant signaling pathways through the TLR4/MD-2 complex.

Conclusions:

• MDS and RIN analyses provide insights into mutant-specific conformational changes in TLR4.
• These findings help elucidate the molecular basis of loss-of-function mutations in TLR4.
• Understanding these dynamics is vital for comprehending innate immune response dysregulation.