Smibert, C.A., Lie, Y.S., Shillinglaw, W., Henzel, W., and Macdonald, P.M. (1999)
Smaug, a novel and conserved protein, contributes to repression of nanos translation in vitro.
RNA 5, 1535-1547.
Abstract
Proper deployment of Nanos protein at the posterior of the Drosophila embryo, where it directs posterior development, requires a combination of RNA localization and translational controls. These controls ensure that only the posteriorly-localized nanos mRNA is translated, while unlocalized nanos mRNA is translationally repressed. Here we describe cloning of the gene encoding Smaug, an RNA binding protein which interacts with the sequences, SREs, in the nanos mRNA that mediate translational repression. Using an in vitro translation assay, we demonstrate that SRE-dependent repression occurs in extracts from early stage embryos. Immunodepletion of Smaug from the extracts eliminates repression, consistent with the notion that Smaug is involved. Smaug is a novel gene and the existence of potential mammalian Smaug homologues raises the possibility that Smaug represents a new class of conserved translational repressor.