Cell Cycle-Dependent TICRR/TRESLIN and MTBP Chromatin Binding Mechanisms and Patterns.

Area of Science:

• Molecular Biology
• Cell Biology
• Genetics

Background:

• DNA replication origin selection is crucial for eukaryotes but poorly understood in humans.
• TICRR/TRESLIN and MTBP are human orthologs of yeast replication initiation factors Sld3 and Sld7.

Purpose of the Study:

• To investigate the genomic binding locations and chromatin association mechanisms of human TRESLIN and MTBP.
• To determine the dependency of TRESLIN and MTBP binding on cell cycle phase and origin licensing.

Main Methods:

• Cut&Run assay was employed to map TRESLIN and MTBP binding sites.
• Experiments utilized asynchronous and G1-synchronized HCT116 colorectal cancer cells.
• Cell lines with inhibited origin licensing (non-degradable inducible Geminin) were used.

Main Results:

• TRESLIN and MTBP binding patterns were more defined in G1-synchronized cells.
• MTBP chromatin association in G1 phase was dependent on TRESLIN.
• TRESLIN and MTBP binding to chromatin did not require loaded MCMs (licensed origins).

Conclusions:

• TRESLIN and MTBP exhibit a TRESLIN-dependent chromatin binding mechanism during G1 phase.
• This mechanism of DNA replication initiation does not rely on pre-licensed origins.