IDENTIFICATION AND CLONING OF A GLUCAN-BINDING AND LIOPOPLYSACCHARIDE-BINDING PROTEIN FROM EISENIA-FOETIDA EARTHWORM INVOLVED IN THE ACTIVATION OF PROPHENOLOXIDASE CASCADE

Coelomic fluid of Eisenia foetida earthworms contains a 42-kDa protein named coelomic cytolytic factor 1 (CCF-1) that was described previous ly to be involved in cytolytic, opsonizing, and hemolytic properties o f the coelomic fluid. Cloning and sequencing of CCF-1 reveal significa nt homology with the putative catalytic region of beta-1,3- and beta-1 ,3-1,4-glucanases. CCF-1 also displays homology with coagulation facto r G from Limulus polyphemus and with Gram-negative bacteria-binding pr otein of Bombyx mori silkworm, two proteins involved in invertebrate d efense mechanisms. We show that CCF-1 efficiently binds both beta-1,3- glucan and lipopolysaccharide, Moreover, CCF-1 participates in the act ivation of prophenoloxidase cascade via recognition of yeast and Gram- negative bacteria cell wall components. These results suggest that the 42-kDa CCF-1 protein of E. foetida coelomic fluid likely plays a role in the protection of earthworms against microbes.