Regulation of Replication Termination in Schizosaccharomyces pombe by Reb1 Protein-Mediated Action at a Distance

摘要

The mechanisms of DNA transactions driven by long range protein-mediated inter and intra-chromosomal interactions are currently of considerable general interest. Here, we report that site-specific replication termination catalyzed by the dimeric Reb1 protein of Schizosaccharomyces. pombe at its cognate replication termini (Ter) did not occur independently at each site but was modulated by the Reb1-mediated interactions between pairs of Ter sites located either in the same or in different chromosomes. The interactions between two Ter sites in cis, placed in a mutually anti-parallel orientation, caused looping out of the intervening DNA in vitro and enhancement of fork arrest in vivo. A Ter on chromosome 2 interacted pair-wise with two Ter sites located on chromosome1 by chromosome kissing. Mutational inactivation of the major interacting Ter on chromosome1 abolished or significantly reduced fork arrest at the Ter site on chromosome 2, thereby revealing a novel mechanism of control of replication termination.