The novel transcription factor e(y)2 interacts with TAF(II)40 and potentiates transcription activation on chromatin templates

Weak hypomorph mutations in the enhancer of yellow genes, e(y)1 and e(y)2, of Drosophila melanogaster were discovered during the search for genes invo lved in the organization of interaction between enhancers and promoters. Pr eviously, the e(y)1 gene was cloned and found to encode TAF(II)40 protein. Here we cloned the e(y)2 gene and demonstrated that it encoded a new ubiqui tous evolutionarily conserved transcription factor. The e(y)2 gene is locat ed at 10C3 (36.67) region and is expressed at all stages of Drosophila deve lopment. It encodes a 101-amino-acid protein, e(y)2. Vertebrates, insects, protozoa, and plants have proteins which demonstrate a high degree of homol ogy to e(y)2. The e(y)2 protein is localized exclusively to the nuclei and is associated with numerous sites along the entire length of the salivary g land polytene chromosomes. Both genetic and biochemical experiments demonst rate an interaction between e(y)2 and TAF(II)40, while immunoprecipitation studies demonstrate that the major complex, including both proteins, appear s to be distinct from TFIID. Furthermore, we provide genetic evidence sugge sting that the carboxy terminus of dTAF(II)40 is important for mediating th is interaction. Finally, using an in vitro transcription system, we demonst rate that recombinant e(y)2 is able to enhance transactivation by GAL4-VP16 on chromatin but not on naked DNA templates, suggesting that this novel pr otein is involved in the regulation of transcription.