COLOCALIZATION OF POLAR REPLICATION FORK BARRIERS AND RIBOSOMAL-RNA TRANSCRIPTION TERMINATORS IN MOUSE RDNA

We investigated the replication of the region where transcription term inates in mouse rDNA. It contains a replication fork barrier (RFB) tha t behaves in a polar manner, arresting only replication forks moving i n the direction opposite to transcription. This RFB consists of severa l closely spaced fork arrest sites that co-localize with the transcrip tion terminator elements, known as Sal boxes. Sal boxes are the target for mTTF-I (murine transcription termination factor I). These results suggest that both termination of rRNA transcription and replication f ork arrest may share cis-acting as well as trans-acting factors. (C) 1 998 Academic Press Limited.