Peptidoglycan Recognition Proteins and Lysozyme

Research output: Chapter in Book/Report/Conference proceedingChapter

8 Scopus citations


Peptidoglycan recognition proteins (PGRPs or PGLYRPs) are evolutionarily conserved innate immunity molecules homologous to bacteriophage type 2 amidases. Mammalian PGRPs are soluble secreted proteins and bind muramyl peptide fragments of bacterial peptidoglycan. Mammalian PGLYRP1, PGLYRP3, and PGLYRP4 are directly bactericidal and kill bacteria by inducing an exaggerated envelope stress response, which causes oxidative, thiol, and metal stress, membrane depolarization, inhibition of biosynthetic reactions, and bacterial death. Mammalian PGLYRP2 is an enzyme, peptidoglycan amidohydrolase. In vivo, mammalian PGRPs maintain a healthy gut microbiome, which protects animals from experimental colitis. Mammalian PGRPs also modulate sensitivity to skin and joint inflammation and allergic asthma. Human PGRP variants are associated with sensitivity to inflammatory bowel diseases, psoriasis, and Parkinson's disease. PGRPs in lower vertebrates, echinoderms, and mollusks are usually bactericidal amidases and protect against infections. PGRPs in insects are more numerous and diverse and are the main sensors of bacterial infections. Insect PGRPs (1) induce signaling cascades (Toll and IMD), which trigger production of antimicrobial peptides; (2) induce the enzymatic prophenoloxidase cascade, which generates other antimicrobial products; and (3) downregulate antimicrobial responses by hydrolyzing stimulatory peptidoglycan or by antagonizing cell-activating receptors. Lysozyme is a peptidoglycan-hydrolyzing muramidase present in all animals. Lysozyme has antibacterial activity and eliminates pro-inflammatory peptidoglycan.

Original languageEnglish (US)
Title of host publicationMolecular Immunology
PublisherElsevier Inc.
Number of pages15
ISBN (Print)9780080921525
StatePublished - Apr 27 2016


  • Amidase
  • Bactericidal
  • Inflammation
  • Lysozyme
  • Muramidase
  • Peptidoglycan recognition protein
  • PGRP

ASJC Scopus subject areas

  • Medicine(all)

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