Two attacin antibacterial genes of Drosophila melanogaster

Insects express a battery of potent antimicrobial proteins in response to i njury and infection. Recent work from several laboratories has demonstrated that this response is neither stereotypic nor completely nonspecific, and that different pathways are responsible for inducing the expression of anti fungal and antibacterial peptides. Here we report the cloning of two closel y linked attacin genes from Drosophila melanogaster. We compare their prote in coding sequences and find the amino acid sequences to be more highly con served than the nucleotide sequences, suggesting that both genes are expres sed. Like other antimicrobial peptides, attacin expression is strongly indu ced in infected and injured flies. Unlike others, attacin transcription is uniquely sensitive to mutations in the 18-Wheeler receptor protein, and thu s may be regulated by a distinct signaling pathway. The number and organiza tion of binding sites for kappa B and other transcription factors in the pr omoter regions of both attacin genes are consistent with strong and rapid i mmune induction. We demonstrate that these promoter regions are sufficient to direct beta-galaclosidase expression in transformed Drosophila third-ins tar larval fat body in a bacterially inducible manner. We present a compari son of the promoter regions of the two attacin genes to those cloned from o ther antimicrobial peptide genes to assist a better understanding of how an timicrobial genes are differentially regulated. (C) 2000 Elsevier Science B .V. All rights reserved.