Sequence and Expression of an Eisenia‐Fetida‐Derived cDNA Clone That Encodes the 40‐kDa Fetidin Antibacterial Protein

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Abstract
Fetidins are 40‐kDa and 45‐kDa hemolytic and antibacterial glycoproteins present in the coelomic fluid of the earthworm Eisenia fetida andrei. By screening a cDNA library with a polyclonal anti‐fetidin serum, we have cloned a cDNA that encoded the 40‐kDa fetidin. The clone contains an insert of 1.44 kb encoding a protein of 34 kDa, which corresponds to the size of deglycosylated fetidins. The recombinant protein inhibits Bacillus megaterium growth. Restriction fragment polymorphisms were observed on Southern blots and correspond to a known protein polymorphism. The sequence of the cDNA contains a peroxidase signature and fetidins from earthworm coelomic fluid have peroxidase activity. The 40‐kDa and 45‐kDa fetidins therefore represent two related polymorphic defence factors in invertebrates.