Identification of a novel TA-rich DNA binding protein that recognizes a TATA sequence within the brain creatine kinase promoter.

The rat brain creatine kinase gene possesses a structurally complex promoter with multiple potential regulatory elements. Two CCAAT sequences, a TATAAATA sequence and a TTAA sequence are found within the first one hundred base pairs. We present evidence that favors the allocation of the downstream TTAA sequence as the potential TATA box. We show that the CCAAT sequences and the upstream TATAAATA sequence are binding sites for potential regulatory factors and that sequences in this region are capable of regulating expression from the downstream TTAA sequence. We suggest that the protein that binds to the upstream TATAAATA sequence is not a classical TFIID factor but rather may serve to block the binding of TFIID and/or to promote transcription from the downstream start site. We have been able to define conditions in vitro under which binding to this upstream TATAAATA sequence does not occur. Under these conditions we are able to detect transcription from both potential TATA sequences, a situation which we have been unable to detect in vivo. Our experiments suggest the existence in HeLa and brain nuclei of a protein that recognizes the concensus TATAAATA sequence, that is distinct from TFIID, and that may function in part to deny access of TFIID to this potential promoter element.