Yeast one-hybrid assay identifies YY1 as a binding factor for a proacrosin promoter element

The proacrosin gene is specifically expressed in the testis and encodes an acrosomal enzyme. Previously, footprint analyses have shown binding of nuclear extracts from testis and brain to a highly conserved 17 bp motif (F1 element: 5'-AACTTCAAAATGGCTCC/T-3') located in the proacrosin promoter. By using this DNA-element as a target in a yeast one-hybrid assay, a cDNA fragment coding for the C-terminal part of the transcription factor YY1 was isolated. The binding of YY1 to this F1 element was confirmed by immunocompetition in EMSA. Because putative YY1 binding sites were also found in the promoters of other testis-specific genes, the YY1 transcription factor could play an important role in testicular gene expression.