A potent inducible antibacterial
peptide carrying an O-glycosylated substitution has recently been isolated from Drosophila [Bulet, P., Dimarcq, J. L., Hetru, C., Lagueux, M., Charlet, M., Hegy, G., Van Dorsselaer, A. and Hoffmann, J. A. (1993) J. Biol. Chem. 268, 14893-14897]. Here we report cloning studies that show that Drosophila contains a single, intronless gene, located at position 51C1-6, which encodes the precursor
protein from which
drosocin is processed. The upstream and the downstream sequences of the
drosocin gene contain putative cis-regulatory elements similar to mammalian regulatory motifs, namely three kappa B-related decameric sequences. The
drosocin gene is silent in naive animals, and is strongly induced with acute phase kinetics after immune challenge in larvae and in adults. We have established several transgenic fly lines in which reporter genes were placed under the control of various
drosocin promoter sequences. Our results indicate that 2.5 kb of upstream sequences confer inducibility and tissue specificity to the transgene, but that the level of its expression in the fat body after immune challenge is low. Addition of genomic regions downstream of the
drosocin transcribed sequences results in increased transcription levels, which are similar for the fusion and the resident
drosocin genes upon
infection. Analysis of transgenic fly lines showed that the
drosocin reporter gene is constitutively expressed in the oviducts of egg-laying females.