Binding of the Treslin-MTBP Complex to Specific Regions of the Human Genome Promotes the Initiation of DNA Replication

In this study, we have mapped the binding sites for the MTBP subunit of the Treslin-MTBP complex throughout the human genome by using the CUT&RUN method. Our results have indicated that MTBP associates reproducibly with several tens of thousands of sites in the genome. Many binding sites contain either G4 DNA or an AP-1 motif in a nucleosome-free region at transcription start sites (TSSs) or enhancers, respectively. In addition, this nucleosome-free region is adjacent to a nucleosome containing certain histone marks characteristic of open chromatin that have also been implicated in initiation. We also mapped early initiation zones with EdU-labeling (EdU-seq) and found that these initiation domains contain a large number of MTBP binding sites. Taken together, these findings indicate that Treslin-MTBP associates with multiple genomic signals to promote initiation of replication. Binding sites of endogenously FLAG-tagged versions of wild-type and C-terminally truncated MTBP were probed with CUT&RUN in triplicate experiments. G1-arrested cells were released into S-phase and early initiation domains were labeled with EdU in the presence of HU and aphidicolin. EdU-labeled DNA was sequenced in triplicate experiments.