Regulated TRESLIN-MTBP loading governs initiation zones and replication timing in human DNA replication

Area of Science:

• Molecular Biology
• Genetics
• Cell Biology

Background:

• Human DNA replication origins cluster into initiation zones (IZs), typically in intergenic regions.
• Chromosome replication follows replication timing (RT), with early replicating euchromatin and late replicating heterochromatin.
• A temporally regulated limiting factor is proposed to explain RT, but remains unidentified in human cells.

Purpose of the Study:

• To investigate the relationship between initiation zones (IZs) and replication timing (RT).
• To identify the limiting factor controlling replication initiation in human cells.
• To elucidate the mechanism regulating IZ firing and RT.

Main Methods:

• Mapping the temporal firing patterns of initiation zones (IZs).
• Examining genome-wide distributions of replication licensing and firing factors.
• Investigating the role of TRESLIN-MTBP in replication initiation.

Main Results:

• TRESLIN-MTBP identified as a key limiting factor for DNA replication initiation.
• TRESLIN-MTBP loading onto phosphorylated MCM2-7 double hexamer (MCM-DH) is crucial.
• Opposing phosphorylation events on MCM-DH by Dbf4-dependent kinase and RIF1-Protein Phosphatase 1 control TRESLIN-MTBP loading.

Conclusions:

• TRESLIN-MTBP acts as the limiting factor in human DNA replication initiation.
• Phosphorylation dynamics of MCM-DH by specific kinases and phosphatases dictate IZ formation and RT.
• This mechanism explains how initiation zones are determined and replication timing is established across the genome.