ANALYSIS OF THE STRUCTURE AND EXPRESSION OF THE TFIIB GENE IN DROSOPHILA-MELANOGASTER

We have isolated and characterized a genomic clone encoding the Drosop hila melanogaster transcription factor IIB (TFIIB). The coding region of the TFIIB gene is interrupted by three short introns. The 5'-flanki ng region of the gene lacks the typical TATA hox sequence like those o f other known genes encoding the general transcription factors. In add ition, the 5'-flanking region of the gene contains several common DNA sequences present in Drosophila TBP and TFIIS genes, suggesting the co mmon regulation mechanism of gene expression, RNA blot analysis reveal ed that the gene expresses 1.6 kb, 1.3 kb and 1.2 kb mRNAs throughout development and in adults, Deletion analysis of the promoter region sh ows that the minimal promoter necessary for efficient expression is lo cated between -698 (PstI) and +60 relative to the transcription start point, Within this minimal promoter region, the upstream regulatory el ement responsible for the stimulation of gene expression may exist in the DNA fragment between -698 (PstI) and -351 (StuI).