A testis-specific transcription factor IIA (TFIIAτ) stimulates TATA-binding protein-DNA binding and transcription activation

The general transcription factor IIA (TFIIA) stimulates RNA polymerase II-specific transcription by stabilizing the association of the TATA-binding protein (TBP) with promoter DNA, inhibiting repressors of TBP, and facilitating activator-dependent conformational changes in the preinitiation complex. TFIIA is encoded by two genes (alpha beta and gamma) that are highly conserved between human and yeast. Here, we report the molecular cloning of a novel human gene that shares significant sequence similarity to the evolutionarily conserved amino- and carboxyl-terminal domains of TFIIA alpha beta. The TFIIA-related protein (TFIIA tau) was cloned from a testis-specific cDNA library, and its mRNA is expressed predominantly in testis tissue as determined by expressed sequence tag data base analysis and Northern blotting analysis. The TFIIA complex reconstituted with the testis-specific subunit, TFIIA (tau+gamma), formed the TFIIA-TBP-TATA DNA (T-A) and TFIIA-TFIIB-TBP-TATA DNA (TAB) complexes indistinguishably hom TFIIA (alpha beta+gamma), TFIIA (tau+gamma) supported basal and activated transcription for most activators in reactions reconstituted with TFIIA-depleted nuclear extracts. However, TFIIA (tau+gamma) was reduced relative to TFIIA (alpha beta+gamma) for stimulating transcription with at least one activator, suggesting that these two forms of TFIIA have activator specificity. These results suggest that TFIIA tau may be important for testis specific transcription regulation.