Peptidoglycan

Overview

Peptidoglycan (murein) is the polymer of N-acetylglucosamine and N-acetylmuramic acid cross-linked by short peptides that forms the bacterial cell wall. It is a major pathogen-associated molecular pattern (PAMP) recognized by host TLR2 (intact peptidoglycan), NOD1 (meso-DAP fragments, Gram-negative), and NOD2 (muramyl dipeptide, both). Peptidoglycan recognition is central to innate immunity and to Crohn's disease (NOD2 mutations) [1].

Metal Connection

  • Peptidoglycan recognition proteins (PGRPs) kill bacteria via three metal-dependent mechanisms: oxidative stress, thiol stress, and osmotic stress. PGRPs activate metal-mediated antimicrobial pathways — a direct intersection of innate immunity and metal toxicity [2].
  • TLR2 signaling: Peptidoglycan-TLR2 activation in the esophagus drives IL-6 and il 8 production [3].

Cross-References

References (3)

  1. Haag LM, Siegmund B (2015). Intestinal Microbiota and the Innate Immune System - a Crosstalk in Crohn's Disease Pathogenesis. Frontiers in Immunology. doi:10.3389/fimmu.2015.00489
  2. Dipika R. Kashyap, Minhui Wang, Li-Hung Liu et al. (2014). Kashyap et al. 2014 — Peptidoglycan Recognition Proteins Kill Bacteria by Inducing Oxidative, Thiol, and Metal Stress. PLoS Pathogens. doi:10.1371/journal.ppat.1004280
  3. Chen S, Jiang D, Zhuang Q et al. (2024). Esophageal microbial dysbiosis impairs mucosal barrier integrity via toll-like receptor 2 pathway in patients with gastroesophageal reflux symptoms. Journal of Translational Medicine. doi:10.1186/s12967-024-05878-1

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