Ligand-induced dimerization of Drosophila peptidoglycan recognition proteins in vitro

• Published in: Proceedings of the National Academy of Sciences - PNAS 2005-05, Vol.102 (18), p.6455-6460
• Main Authors: Mellroth, P, Karlsson, J, Hakansson, J, Schultz, N, Goldman, W.E, Steiner, H
• Format: Article
• Language: English
• Subjects: animal proteins; Animals; Bacteria; Bacteria - immunology; Bacteria - metabolism; binding proteins; Biological Sciences; Carrier Proteins - metabolism; Cell Line; Cell lines; Cell Wall - metabolism; Dimerization; Dimers; Drosophila; Drosophila - immunology; Drosophila - metabolism; Drosophila - microbiology; Drosophila melanogaster; Gels; Gene expression; Genetic Vectors - genetics; Geometric lines; Immune system; immunity; Immunohistochemistry; Insects; Laboratory staining techniques; Ligands; Models, Biological; Mutation; Organophosphorus Compounds; Peptidoglycan - metabolism; peptidoglycans; polysaccharides; Proteins; Receptors; Sequence Analysis, Protein; Signal Transduction - immunology
• ISSN: 0027-8424; 1091-6490; 1091-6490
• DOI: 10.1073/pnas.0407559102

Drosophila knockout mutants have placed peptidoglycan recognition proteins (PGRPs) in the two major pathways controlling immune gene expression. We now examine PGRP affinities for peptidoglycan. PGRP-SA and PGRP-LCx are bona fide pattern recognition receptors, and PGRP-SA, the peptidoglycan receptor of the Toll/Dif pathway, has selective affinity for different peptidoglycans. PGRP-LCx, the default peptidoglycan receptor of the Imd/Relish pathway, has strong affinity for all polymeric peptidoglycans tested and for monomeric peptidoglycan. PGRP-LCa does not have affinity for polymeric or monomeric peptidoglycan. Instead, PGRP-LCa can form heterodimers with LCx when the latter is bound to monomeric peptidoglycan. Hence, PGRP-LCa can be said to function as an adaptor, thus adding a new function to a member of the PGRP family.