Journal of Enzyme Inhibition and Medicinal Chemistry (Dec 2024)

o-Vanillin binds covalently to MAL/TIRAP Lys-210 but independently inhibits TLR2

  • Md. Habibur Rahaman,
  • Sara J. Thygesen,
  • Michael J. Maxwell,
  • Hyoyoung Kim,
  • Prerna Mudai,
  • Jeffrey D. Nanson,
  • Xinying Jia,
  • Parimala R. Vajjhala,
  • Andrew Hedger,
  • Irina Vetter,
  • Thomas Haselhorst,
  • Avril A. B. Robertson,
  • Brian Dymock,
  • Thomas Ve,
  • Mehdi Mobli,
  • Katryn J. Stacey,
  • Bostjan Kobe

DOI
https://doi.org/10.1080/14756366.2024.2313055
Journal volume & issue
Vol. 39, no. 1

Abstract

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AbstractToll-like receptor (TLR) innate immunity signalling protects against pathogens, but excessive or prolonged signalling contributes to a range of inflammatory conditions. Structural information on the TLR cytoplasmic TIR (Toll/interleukin-1 receptor) domains and the downstream adaptor proteins can help us develop inhibitors targeting this pathway. The small molecule o-vanillin has previously been reported as an inhibitor of TLR2 signalling. To study its mechanism of action, we tested its binding to the TIR domain of the TLR adaptor MAL/TIRAP (MALTIR). We show that o-vanillin binds to MALTIR and inhibits its higher-order assembly in vitro. Using NMR approaches, we show that o-vanillin forms a covalent bond with lysine 210 of MAL. We confirm in mouse and human cells that o-vanillin inhibits TLR2 but not TLR4 signalling, independently of MAL, suggesting it may covalently modify TLR2 signalling complexes directly. Reactive aldehyde-containing small molecules such as o-vanillin may target multiple proteins in the cell.

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