Identification of a DNA sequence element required for efficient expression of a developmentally regulated and cAMP-inducible gene of Dictyostelium discoideum.

The cysteine proteinase 2 gene of Dictyostelium encodes a developmentally regulated sulphydryl proteinase which is first expressed late during cellular aggregation. The mRNA is slightly enriched in pre-stalk over pre-spore cells but we show here that it is expressed at a somewhat higher level in mature spore cells than in stalk cells. The mRNA is induced to accumulate precociously in response to exogenous cAMP and we show that a fragment of DNA containing 921 nucleotides upstream of the major start site of transcription directs regulated expression of the gene. Approximately 200 nucleotides upstream of the cap site there are two, adjacent, homologous G-rich regions of 9 nucleotides in length. We have constructed small internal deletions and point mutations which affect the distal element. We find a major reduction in regulated transcription indicating this element to be important in mediating cAMP induction of gene expression.