Compatibility between enhancers and promoters determines the transcriptional specificity of gooseberry and gooseberry neuro in the Drosophila embryo.

The two Drosophila genes gooseberry (gsb) and gooseberry neuro (gsbn) are closely apposed and divergently transcribed. While gsb is a segment-polarity gene and mainly expressed in the epidermis, gsbn is expressed in the central nervous system. An intriguing question is how their transcriptional specificity arises. Here we show that different non-overlapping enhancer or upstream control elements drive the specific expression of gsb and gsbn. Specificity of these enhancers for their genes is achieved by their inability to activate transcription in combination with the heterologous promoter of the other gene. These results therefore suggest that compatibility between the enhancer and its cognate promoter is a mechanism ensuring transcriptional specificity.