N-terminal KTKEGV motif lysine residues of α-Synuclein are critical for TLR2 interaction and activation.

Synucleinopathies, such as Parkinson's Disease, involve widespread intracellular protein aggregates. α-synuclein (αSyn) protein contributes majorly to these aggregates called as Lewy Bodies, which are linked to neurodegeneration. αSyn has been shown to transmit from infected to healthy neurons, thus spreading the pathology. During its transmission, αSyn is also known to activate microglia by interacting with the glial surface receptors such as Toll-Like receptors (TLRs). This activation is implicated in the production of interleukins and proinflammatory cytokines, exacerbating neuronal death through chronic neuroinflammation. However, the mechanism of αSyn and TLR interaction is not well elucidated. In this study, using biophysical methods and in the HEK-TLR2 cells, we demonstrate that αSyn N-terminal has a higher binding affinity with TLR2. This interaction is mediated through the lysine residues in the second and third KTKEGV motifs of αSyn. The lysine to alanine mutations in the N-terminal KTKGEV motifs perturb the αSyn/TLR2 interaction. We also demonstrate that the lysine residues of 2nd and 3rd KTKEGV motifs are critical for αSyn-mediated TLR2 activation. Our study demonstrates that the N-terminal KTKEGV lysine residues facilitate interaction with TLR2, thereby regulating αSyn-mediated neuroinflammation.