scholarly journals Crystal structure and interactions of the Tof1–Csm3 (Timeless–Tipin) fork protection complex

2020 ◽  
Vol 48 (12) ◽  
pp. 6996-7004 ◽  
Author(s):  
Daniel B Grabarczyk
Keyword(s):  
Crystal Structure ◽  
Circadian Rhythm ◽  
Dna Replication ◽  
Binding Site ◽  
Molecular Basis ◽  
Replication Forks ◽  
Repeat Structure ◽  
Chaetomium Thermophilum ◽  
Fork Protection Complex ◽  
Human Orthologue

Abstract The Tof1–Csm3 fork protection complex has a central role in the replisome—it promotes the progression of DNA replication forks and protects them when they stall, while also enabling cohesion establishment and checkpoint responses. Here, I present the crystal structure of the Tof1–Csm3 complex from Chaetomium thermophilum at 3.1 Å resolution. The structure reveals that both proteins together form an extended alpha helical repeat structure, which suggests a mechanical or scaffolding role for the complex. Expanding on this idea, I characterize a DNA interacting region and a cancer-associated Mrc1 binding site. This study provides the molecular basis for understanding the functions of the Tof1–Csm3 complex, its human orthologue the Timeless–Tipin complex and additionally the Drosophila circadian rhythm protein Timeless.

scholarly journals Crystal structure of the Tof1-Csm3 (Timeless-Tipin) fork protection complex

2020 ◽  
Author(s):  
Daniel B. Grabarczyk
Keyword(s):  
Crystal Structure ◽  
Peptide Binding ◽  
Replication Forks ◽  
Binding Properties ◽  
Helical Bundle ◽  
Chaetomium Thermophilum ◽  
Fork Protection Complex ◽  
Peptide Binding Site ◽  
Human Orthologue ◽  
Dna Binding Properties

AbstractThe Tof1-Csm3 fork protection complex has a central role in the replisome – it promotes the progression of DNA replication forks and protects them when they stall, while also enabling cohesion establishment and checkpoint responses. Here, I present the crystal structure of the Tof1-Csm3 complex from Chaetomium thermophilum at 3.1 Å resolution. The structure reveals that Tof1 is an extended alpha-helical repeat protein which is capped at its C-terminal end by Csm3, a small helical bundle protein. I also characterize the DNA binding properties of the complex and a cancer-associated peptide-binding site. This study provides the molecular basis for understanding the functions of the Tof1-Csm3 complex, its human orthologue the Timeless-Tipin complex and additionally the Drosophila circadian rhythm protein Timeless.

scholarly journals SDE2 Integrates into the TIMELESS-TIPIN Complex to Protect Stalled Replication Forks

2020 ◽  
Author(s):  
Julie Rageul ◽  
Jennifer J. Park ◽  
Ping Ping Zeng ◽  
Eun-A Lee ◽  
Jihyeon Yang ◽  
...  
Keyword(s):  
Dna Replication ◽  
Replication Fork ◽  
Genome Stability ◽  
Essential Role ◽  
Replication Stress ◽  
Replication Forks ◽  
Genomic Integrity ◽  
Fork Protection Complex ◽  
Stalled Replication Forks ◽  
Stalled Fork

ABSTRACTProtecting replication fork integrity during DNA replication is essential for maintaining genome stability. Here, we report that SDE2, a PCNA-associated protein, plays a key role in maintaining active replication and counteracting replication stress by regulating the replication fork protection complex (FPC). SDE2 directly interacts with the FPC component TIMELESS (TIM) and enhances TIM stability and its localization to replication forks, thereby aiding the coordination of replisome progression. Like TIM deficiency, knockdown of SDE2 leads to impaired fork progression and stalled fork recovery, along with a failure to activate CHK1 phosphorylation. Moreover, loss of SDE2 or TIM results in an excessive MRE11-dependent degradation of reversed forks. Together, our study uncovers an essential role for SDE2 in maintaining genomic integrity by stabilizing the FPC and describes a new role for TIM in protecting stalled replication forks. We propose that TIM-mediated fork protection may represent a way to cooperate with BRCA-dependent fork stabilization.

scholarly journals SDE2 integrates into the TIMELESS-TIPIN complex to protect stalled replication forks

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Julie Rageul ◽  
Jennifer J. Park ◽  
Ping Ping Zeng ◽  
Eun-A Lee ◽  
Jihyeon Yang ◽  
...  
Keyword(s):  
Dna Replication ◽  
Replication Fork ◽  
Genome Stability ◽  
Essential Role ◽  
Replication Stress ◽  
Replication Forks ◽  
Genomic Integrity ◽  
Fork Protection Complex ◽  
Stalled Replication Forks ◽  
Stalled Fork

Abstract Protecting replication fork integrity during DNA replication is essential for maintaining genome stability. Here, we report that SDE2, a PCNA-associated protein, plays a key role in maintaining active replication and counteracting replication stress by regulating the replication fork protection complex (FPC). SDE2 directly interacts with the FPC component TIMELESS (TIM) and enhances its stability, thereby aiding TIM localization to replication forks and the coordination of replisome progression. Like TIM deficiency, knockdown of SDE2 leads to impaired fork progression and stalled fork recovery, along with a failure to activate CHK1 phosphorylation. Moreover, loss of SDE2 or TIM results in an excessive MRE11-dependent degradation of reversed forks. Together, our study uncovers an essential role for SDE2 in maintaining genomic integrity by stabilizing the FPC and describes a new role for TIM in protecting stalled replication forks. We propose that TIM-mediated fork protection may represent a way to cooperate with BRCA-dependent fork stabilization.

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