Distinct carbohydrate recognition domains of an invertebrate defense molecule recognize Gram-negative and Gram-positive bacteria.

摘要: Coelomic fluid of Eisenia foetida earthworms (Oligochaeta, Annelida) contains a 42-kDa defense molecule named CCF for coelomic cytolytic factor. By binding microbial antigens, namely the O-antigen lipopolysaccharide (LPS), beta-1,3-glucans, or N,N'-diacetylchitobiose present, respectively, on Gram-negative bacteria yeast cell walls, triggers prophenoloxidase activating pathway. We report that recognizes lysozyme-predigested Gram-positive peptidoglycan constituent muramyl dipeptide as well muramic acid. To identify pattern recognition domains CCF, deletion mutants were tested their ability to reconstitute cascade in E. depleted endogenous presence LPS, N,N'-diacetylchitobiose, and In addition, affinity chromatography peptides was performed immobilized beta-1,3-glucans N,N'-diacetylchitobiose. found broad specificity pathogen-associated molecular patterns results from two distinct domains. One domain, which shows homology with polysaccharide glucanase motifs beta-1,3-glucanases invertebrate molecules located central part polypeptide chain, interacts LPS beta-1,3-glucans. The C-terminal tryptophan-rich domain mediates interactions These data provide evidence spatially carbohydrate within this molecule.