Identification of engrailed promoter elements essential for interactions with a stripe enhancer in Drosophila embryos.
BACKGROUND
The structures and functions of promoter sequences of most genes have been analysed using in vitro transcription and/or cultured cell systems, neither possessing tissue-specific enhancers. Promoter-enhancer interactions in vivo, in particular, during ontogeny, are still poorly understood.


RESULTS
We have established a new method for the assessment of promoter activity in cells that participate in fly body formation, using the UAS/GAL4 system. A functional analysis was then conducted on the promoter sequence of the engrailed gene in Drosophila embryos. A 38-bp-long sequence, terminating with an initiator or RNA start site and a downstream promoter element, was found to be capable of receiving activation signals from the engrailed stripe enhancer. Transcriptional efficiency was improved significantly by the presence of upstream promoting elements, most functionally replaceable with synthetic GAGA factor binding sites.


CONCLUSIONS
We identified the in vivo minimum promoter of engrailed and demonstrated that the GAGA factor binding sites serve primarily as quantitative elements which augment transcriptional efficiency. Evidence was also obtained that indicated that not only enhancer but also promoter sequences were involved in the determination of the tissue-specificity of gene expression.
Orihara
M
M
Department of Biophysics and Biochemistry, Graduate School of Science, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.
Hosono
C
C
Kojima
T
T
Saigo
K
K
D000818:Animals; D001483:Base Sequence; D004268:DNA-Binding Proteins / Q000235:genetics*; D004330:Drosophila / Q000196:embryology / Q000235:genetics*; D029721:Drosophila Proteins; D004742:Enhancer Elements, Genetic; D018507:Gene Expression Regulation, Developmental; D017344:Genes, Insect; D018840:HSP70 Heat-Shock Proteins / Q000235:genetics / Q000378:metabolism; D018398:Homeodomain Proteins / Q000235:genetics* / Q000378:metabolism; D008969:Molecular Sequence Data; D011401:Promoter Regions, Genetic; D014157:Transcription Factors / Q000235:genetics* / Q000378:metabolism; D014158:Transcription, Genetic; D015533:Transcriptional Activation
D004268:DNA-Binding Proteins; D029721:Drosophila Proteins; C063459:En protein, Drosophila; D018840:HSP70 Heat-Shock Proteins; D018398:Homeodomain Proteins; D014157:Transcription Factors; C063460:Trl protein, Drosophila; C096359:sr protein, Drosophila