Biology subjects

Terui, R.

Publications and source records attributed to Terui, R..

3 recordsLinked to original sources

bioRxiv2026

TOPBP1-Dependent DNA Damage Processing Promotes Centromere Loss in an Inviable Xenopus Hybrid

Hybrid incompatibility is associated with chromosome instability, DNA damage, and embryonic lethality, yet how cells respond to genome instability in hybrids is unclear. In inviable hybrids generated by fertilizing Xenopus tropicalis eggs with Xenopus laevis sperm, CENP-A is lost from paternal chromosomes, leading to elimination of two chromosome arms. Using hybrid Xenopus egg extract reactions, we show that CENP-A is removed from X. laevis chromosomes exposed to X. tropicalis cytoplasm through an RNA polymerase II-dependent process associated with DNA damage. Topoisomerase II Binding Protein 1 (TOPBP1) localized to damaged acentric chromosomes during metaphase, and its depletion impaired chromosome alignment, increased DNA damage, and blocked CENP-A removal. Inhibition of DNA polymerase theta increased DNA damage while promoting CENP-A retention, indicating that DNA damage processing rather than damage itself promotes CENP-A loss. Together, our findings reveal separable roles for TOPBP1 in chromosome organization and centromere destabilization, showing how a protective genome surveillance pathway can instead drive chromosome instability in an inviable hybrid.

cell biology↗

bioRxiv2025

Mcm10 and RecQL4 Synergize to Activate the Eukaryotic Replicative DNA Helicase

Chromosomes are copied from thousands of origins. At each origin, two replicative DNA helicases are first assembled, then activated to begin unwinding DNA. Several replication proteins are subsequently recruited to the active helicase, forming a replisome. The helicase must undergo dramatic conformational changes during its activation and this process is poorly understood, especially in metazoa. How the metazoan replicative helicase is activated, and which proteins promote this essential process are long-standing questions. Using a combination of single-molecule imaging and ensemble biochemistry, we show that Mcm10 and RecQL4 act in a concerted manner to activate replicative helicases. Mcm10 first binds to inactive helicases, then recruits RecQL4, which synergizes with Mcm10 to promote helicase activation. Mcm10 is not incorporated into replisomes and dissociates from origins during replication initiation. In the absence of Mcm10, RecQL4 is recruited to origins via an interaction with the Mcm7 subunit of the helicase. Our data reveal that Mcm10 and RecQL4 play partially redundant roles during helicase activation, help resolve long-standing controversies about the roles of Mcm10 and RecQL4 in DNA replication, and reveal replication initiation defects caused by pathologic RecQL4 mutations.

molecular biology↗

bioRxiv2024

Single-Molecule Imaging Reveals the Mechanism of Bidirectional Replication Initiation in Metazoa

Metazoan genomes are copied bidirectionally from thousands of replication origins. Replication initiation entails the assembly and activation of two CMG (Cdc45*Mcm2-7*GINS) helicases at each origin. This requires several firing factors (including TopBP1, RecQL4, DONSON) whose exact roles remain unclear. How two helicases are correctly assembled and activated at every single origin is a long-standing question. By visualizing the recruitment of GINS, Cdc45, TopBP1, RecQL4, and DONSON in real time, we uncovered a surprisingly dynamic picture of initiation. Firing factors transiently bind origins but do not travel with replisomes. Two Cdc45 simultaneously arrive at each origin and two GINS are recruited together, even though neither protein can dimerize. The synchronized delivery of two GINS is mediated by DONSON, which acts as a dimerization scaffold. We show that RecQL4 promotes DONSON dissociation and facilitates helicase activation. The high fidelity of bidirectional origin firing can be explained by a Hopfield-style kinetic proofreading mechanism.

molecular biology↗