The In's and Out's on Pathogen Screening

Science's STKE  10 Jun 2003:
Vol. 2003, Issue 186, pp. tw225-TW225
DOI: 10.1126/stke.2003.186.tw225

All multicellular organisms have common families of mechanisms that operate during early stages of responses to pathogen attack. Studies in insects and mammals have revealed the role of the Toll family and of the pattern recognition molecules Nod 1 and 2 in activating similar, but not identical, signal-transduction pathways. Lipopolysaccharide is not the sole pattern recognized by the innate immune system, Girardin et al. show that intracellular Nod1 specifically detects a tripeptide bearing an exposed diaminopimelate amino acid derived from the peptidoglycan of Gram-negative bacteria. In contrast, Nod2, which is present on monocytes, macrophages, and dendritic cells senses a peptidoglycan dipeptide motif common to all bacteria (unresponsive mutants of Nod2 have been implicated in Crohn's disease). Thus, Nod1 allows discrimination between intracellular Gram-positive and Gram-negative microorganisms and helps to shape subsequent adaptive immune responses.

S. E. Girardin, I. G. Boneca, L. A. M. Carneiro, A. Antignac, M. Jéhanno, J. Viala, K. Tedin, M.-K. Taha, A. Labigne, U. Zäthringer, A. J. Coyle, P. S. DiStefano, J. Bertin, P. J. Sansonetti, D. J. Philpott, Nod1 detects a unique muropeptide from Gram-negative bacterial peptidoglycan, Science 300, 1584-1587 (2003). [Abstract] [Full Text]