Mutational analysis reveals that an array of GCAAG/CTTGC motifs between sprit promoter sequences for RNA polymerase III is essential for neural BC1 RNA transcription

BC1 RNA is expressed from an identifier (ID) sequence by RNA polymerase III (Pol III) and occurs in neural cells as a ribonucleoprotein particle (BC1 RNP). On the BC1 RNA gene, between the Pol III promoter A and B boxes, there is a region which contains short inverted repeats, including three GCAAG/CTTGC motifs. We found that a nuclear protein binds specifically to this region and, using an in vitro transcription system, demonstrated that point mutations within these motifs markedly inhibit BC1 RNA transcription. These results suggest that the GCAAG/CTTGC motif region and its binding protein may play a role in the transcription of BC1 RNA. Moreover, we demonstrated that transcription is repressed by a concomitant molar excess of BC1 RNA and that the BC1 RNA transcribed by this system forms an RNP with nuclear protein(s), suggesting some interaction of BC1 RNA with transcription factor(s). (C) 1997 Academic Press.