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Semi-Quantitative Analysis of Peptidoglycan by Liquid Chromatography Mass Spectrometry and Bioinformatics
09:09

Semi-Quantitative Analysis of Peptidoglycan by Liquid Chromatography Mass Spectrometry and Bioinformatics

Published on: October 13, 2020

A peptidoglycan monomer with the glutamine to serine change and basic peptides bind in silico to TLR-2 (403-455)

Yufeng Li1, Clay L Efferson, Rajagopal Ramesh

  • 1Department of Melanoma Medical Oncology, The University of Texas MD Anderson Cancer Center, 1515 Holcombe Blvd, Houston, TX 77030, USA. yim_lee80@hotmail.com

Cancer Immunology, Immunotherapy : CII
|December 29, 2010
PubMed

Insights

Novel peptides can block bacterial cell wall components from activating Toll-like receptor 2 (TLR-2). This discovery in molecular modeling could lead to new vaccine adjuvants and cancer therapies by targeting TLR-2 signaling.

Area of Science:

  • Immunology
  • Molecular Biology
  • Structural Biology

Background:

  • Bacterial cell wall polysaccharides, like peptidoglycan (PGN), activate monocytes/macrophages via receptors such as Toll-like receptor 2 (TLR-2).
  • TLR-2 recognizes various ligands, including lipopeptides and bacterial glycoproteins, but specific binding sites for soluble PGN remain undefined.
  • Peptides encountered in vivo may pre-form TLR-2, influencing its response to activators.

Purpose of the Study:

  • To identify potential binding sites for peptides and monomeric PGN on the extracellular domain (ECD) of TLR-2.
  • To understand the molecular interactions between these peptides, PGN, and TLR-2.
  • To lay the groundwork for developing synthetic adjuvants for vaccines and cancer therapies.

Main Methods:

  • In silico molecular docking of peptides and PGN monomer (PGN-S-monomer) to the ECD of TLR-2.
  • Computational quantification of binding free energy (DG) to identify candidate binding sites.
  • Analysis of molecular models to visualize insertion and interaction of PGN and peptides within TLR-2.

Main Results:

  • Two distinct binding sites were identified for peptides and PGN on TLR-2.
  • The PGN-S-monomer binds to TLR-2 residues 404-430 (most closely 417-428), with N-acetyl-glucosamine (NAG) inserting deeply and lysine interacting with Glu(403) and Tyr(378).
  • Peptides bind to TLR-2 residues 434-455, with N-terminal arginines or C-terminal tyrosines interacting with the TLR-2 coil. PGN also shows low-affinity binding at other sites, distinct from the lipopeptide site.

Conclusions:

  • This study presents the first identification of candidate binding sites for monomeric PGN and specific peptides on TLR-2.
  • The findings suggest that peptides can interfere with PGN binding and activation of TLR-2.
  • Experimental validation is crucial for developing synthetic PGN-based adjuvants that can target both adjuvant and cancer antigens to TLR-2.

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