Molecular characterization of ceratotoxin C, a novel antibacterial female-specific peptide of the ceratotoxin family from the medfly Ceratitis capitata

Ceratotoxins A and B are antibacterial peptides produced by the sexually mature females of Ceratitis capitata. The gene expression is restricted to the female reproductive accessory glands, and is not affected by bacterial infection, but is enhanced by mating. We report here the purification and the amino acid sequence of ceratotoxin C, a novel member of the ceratotoxin family, the cloning of its cDNA and the analysis of its expression. Ceratotoxin C is coordinately expressed with the other members of the ceratotoxin family. Its antibacterial activity is directed against both Gram-negative and Gram-positive bacterial strains but it is lower than that of ceratotoxin A. We demonstrate in the genome of C. capitata the presence of at least three ceratotoxin genes which express, in the female accessory glands, a set of peptides presumably involved in the protection of the genital tract during fertilization.