Closely related DNA sequences specify distinct patterns of developmental expression in Drosophila melanogaster.

Abstract

Three short synthetic DNA sequences, which are closely related to one another, confer three distinct patterns of developmental expression on the heat shock hsp7O gene in transgenic Drosophila melanogaster lines. These results show that small variations or even single base pair changes in a repeated element of a regulatory sequence can create promoters that display new specificities of tissue and developmental regulation. Interestingly, the three patterns of developmental expression conferred by the synthetic DNAs resemble in part those of the known developmental genes: glucose dehydrogenase (Gld), Dopa decarboxylase (Ddc), and salivary gland secretory proteins (Sgs), respectively. In each case, the defined regulatory region of the known developmental gene contains multiple sequences that are similar or identical to the synthetic sequence that confers a similar pattern of developmental expression on the hsp7O gene. Thus, these results are congruent with the view that short sequence elements in multiple copies can confer either simple or relatively complex patterns of developmental expression on a receptive promoter like that of hsp7O. Furthermore, the fact that the three variants tested produced three distinct patterns of expression in transgenic animals suggests that the number of different elements is large.Regulatory regions of genes contain multiple short sequence elements that are binding sites for specific regulatory proteins (19,24,32). These binding interactions are determined in large part by both the affinity of the proteins for particular sequence elements and the abundance of these proteins in the particular cell type in question. The effect of these protein-DNA interactions on transcription depends on the transcriptional activation (or repression) strength of a protein and on the constellation of such protein-DNA complexes that are associated with a particular gene (32). The number of distinct regulatory proteins that have been identified to interact with specific DNA sequence elements is large and growing rapidly, particularly in the cases of multicellular organisms (1,9,15,19,21,22,24,32,35). Many of these regulatory proteins possess similar structural domains that mediate binding to specific DNA sequences (9,21,22,32,33) and are, in at least some cases, encoded by members of large evolutionarily related gene families (1,22 shock-induced developmental expression of the introduced hsp7O-lacZ genes that are conferred by the synthetic regulatory sequences. We show that each of the three synthetic sequence variants of the heat shock element that we examined confers a distinct pattern of developmental expression in transgenic Drosophila lines.The heat shock gene hsp7O in D. melanogaster appears to be exclusively under heat shock control (16, 27, 41); however, the hsp7O promoter that is deleted of its native heat shock regulatory sequence has been shown to be a very receptive target for activation by a variety of regulatory elements (7,10,12,26). Figure 1A shows the structure of the hsp7O-lacZ transposon...

The Expression of Heat Shock Protein and Cognate Genes During Plant Development

“…There are cases of altered spacing as well as multiple HSEs in both plant and animal systems . Recent work by Xiao and Lis (1990) demonstrates that minor changes in a Drosophila HSE can direct organ specific expression in the absence of heat stress. Although Czarnecka et al (1989) and Schoff!…”