DROSOPHILA IMMUNITY - A COMPARATIVE-ANALYSIS OF THE REL PROTEINS DORSAL AND DIF IN THE INDUCTION OF THE GENES ENCODING DIPTERICIN AND CECROPIN

In Drosophila, bacterial challenge induces the rapid transcription of several genes encoding potent antibacterial peptides, The upstream seq uences of the diptericin and cecropin Al genes, which have been invest igated in detail, contain two, respectively one sequence element homol ogous to the binding site of the mammalian nuclear factor kappa B, The se elements have been shown to be mandatory for immune-induced transcr iption of both genes, Functional studies have shown that these kappa B -related elements can be the target for the Drosophila Rel proteins do rsal and Dif, Here we present a comparative analysis of the transactiv ating capacities of these proteins on reporter genes fused to either t he diptericin or the cecropin kappa B-related motifs, We conclude from our results: (i) the kappa B motifs Of the diptericin and cecropin ge nes are not functionally equivalent; (ii) the dorsal and Dif proteins have distinct DNA-binding characteristics; (iii) dorsal and Dif can he terodimerize in vitro; (vi) mutants containing no copies of dorsal and a single copy of Dif retain their full capacity to express the dipter icin and cecropin genes in response to challenge.