Expression and regulation of Spatzle-processing enzyme in Drosophila

The Drosophila melanogaster Toll receptor controls embryonic dorsal-ventral axis formation and is crucial for the innate immune response. In both cases, Toll is activated by the enzymatically cleaved form of its ligand Spatzle (Spz). During axis formation, Spz is cleaved by the maternally provided serine protease Easter while the Spatzle-processing enzyme (SPE) activates Spz after infection. We confirm the role of SPE in immunity and show that it is a zygotic gene specifically expressed in immune tissues implying that the dual activation of Spz is achieved by differential spatiotemporal expression of two similar but distinct serine proteases. (c) 2006 Federation of European Biochemical Societies. Published by Elsevier B.V. All rights reserved.