Pattern recognition receptors, which recognize conserved components found in pathogens but not in the host, are central to the innate immune response. Chang et al. describe the crystal structure at 2.1 angstrom resolution of tracheal cytotoxin (TCT), a fragment of a peptidoglycan specific to Gram-negative bacteria, bound to the ectodomains of the peptidoglycan recognition proteins LCa and LCx. The structure shows how a specificity determinant of Gram-negative bacteria is recognized in the complex and how TCT induces heterodimerization of LCa and LCx to activate downstream signaling.
C.-I Chang, Y. Chelliah, D. Borek, D. Mengin-Lecreulx, J. Deisenhofer, Structure of tracheal cytotoxin in complex with a heterodimeric pattern-recognition receptor. Science 311, 1761-1764 (2006). [Abstract] [PubMed]