Peptidoglycan activation of the proPO-system without a peptidoglycan receptor protein (PGRP)?
2011 (English)In: Developmental and Comparative Immunology, ISSN 0145-305X, E-ISSN 1879-0089, Vol. 35, no 1, 51-61 p.Article in journal (Refereed) Published
Recognition of microbial polysaccharide by pattern recognition receptors triggers the prophenoloxidase (proPO) cascade, resulting in melanin synthesis and its deposition on the surface of invading pathogens. Several masquerade-like proteins and serine proteinase homologues have been shown to be involved in the proPO activation in insects. In this study, a novel serine proteinase homologue, Pl-SPH2, was found and isolated as a 30 kDa protein from hemocytes of the freshwater crayfish, Pacifastocus leniusculus, by its binding property to a partially lysozyme digested or TCA-treated insoluble Lysine (Lys)-type pepticloglycan (PGN) and soluble polymeric Lys-type PGN. Two other proteins, the Pl-SPH1 and lipopolysaccharide- and beta-1,3-glucan-bincling protein (LGBP) were also found in the several different PGN-binding assays. However no PGRP homologue was detected. Neither was any putative PGRP found after searching available crustacean sequence databases. If RNA interference of Pl-SPH2, Pl-SPH1 or LGBP in the crayfish hematopoietic tissue cell culture was performed, it resulted in lower PO activity following activation of the proPO-system by soluble Lys-type PGN. Taken together, we report for the first time that Lys-type PGN is a trigger of proPO-system activation in a crustacean and that two Pl-SPlis are involved in this activation possibly by forming a complex with LGBP and without a PGRP.
Place, publisher, year, edition, pages
2011. Vol. 35, no 1, 51-61 p.
Innate immunity, Lys-type PGN, PGRP, proPO, SPHs
Research subject Biology with specialization in Comparative Physiology
IdentifiersURN: urn:nbn:se:uu:diva-140158DOI: 10.1016/j.dci.2010.08.005ISI: 000285024400007PubMedID: 20713082OAI: oai:DiVA.org:uu-140158DiVA: diva2:383100