Structures of Drosophila virilis TBP and TFIIB Genes and the Comparison with the Drosophila melanogaster Genes

The Drosophila virilis TFIIB and TBP genes were isolated and sequenced. The D. virilis TFIIB gene encodes a protein of 293 amino acids and contains three small introns, located in the exactly corresponding sites as the three introns in D. melanogaster TFIIB gene. The D. virilis TFIIB protein showed 97% sequence identity to D. melanogaster protein, although a stretch of 22 amino acids present is missing in the D. virilis protein. The D. virilis TBP gene encodes a protein of 349 amino acids and its exon-intron structure is identical to that of D. melanogaster TBP gene. The deduced amino acid sequence of D. virilis TBP indicates a high degree of homology with D. melanogaster TBP (77% identity). The carboxy-terminal domain of the D. virilis TBP is 95% identical to that of D. melanogaster protein whereas the amino-terminal domains of the two proteins is much less conserved. Our data suggest that the gene structures and protein sequences of TFIIB and TBP are well conserved in D. virilis and D. melanogaster and that the functions of these two proteins are well conserved in these distantly related Drosophila species.