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Transcriptional activation through interaction of MBF2 with TFIIA
Author(s) -
Li FengQian,
Takemaru Kenichi,
Goto Masahide,
Ueda Hitoshi,
Handa Hiroshi,
Hirose Susumu
Publication year - 1997
Publication title -
genes to cells
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.912
H-Index - 115
eISSN - 1365-2443
pISSN - 1356-9597
DOI - 10.1046/j.1365-2443.1997.1090306.x
Subject(s) - biology , transcription factor ii a , computational biology , microbiology and biotechnology , genetics , promoter , gene , gene expression
Background: Transcriptional activation of the Drosopohila melanogaster fushi tarzu gene by FTZ‐F1 or its silkworm counterpart BmFTZ‐F1 requires two cofactors MBF1 and MBF2 which do not directly bind to DNA. MBF1 is a bridging molecule that connects FTZ‐F1 (or BmFTZ‐ F1), MBF2 and TATA binding protein TBP. MBF2 is a positive cofactor that activates transcription. Results : To elucidate the mechanism of transcriptional activation by MBF2, we isolated a cDNA coding for the factor. Northern blot analyses showed temporally restricted expression of MBF2 mRNA similar to that of BmFTZ‐F1 mRNA. The cDNA sequence predicts a polypeptide of 10 kDa whereas natural MBF2 is a glycoprotein of 22 kDa. The deduced amino acid sequence of the factor showed no homology with proteins in the databases. Farwestern analyses and glutathione S –transferase interaction assays demonstrated that MBF2 makes a direct contact with the β‐subunit of TFIIA. In a HeLa cell nuclear extract, bacterially expressed recombinant MBF2 activated transcription from various promoters as natural MBF2 did. This activation requires the MBF2–TFIIA interaction. When recombinant MBF2 was added to the HeLa cell nuclear extract in the presence of MBF1 and FTZ622 bearing the DNA‐binding region of FTZ‐F1, it selectively activated transcription of the fushi tarazu gene. This selective activation also requires the MBF2–TFIIA interaction. Conclusion : MBF2 activates transcription through its interaction with TFIIA. Selective transcriptional activation occurs when MBF2 is recruited to a promoter carrying the FTZ‐F1 binding site by FTZ‐F1 and MBF1.