CST/Polα/primase-mediated fill-in synthesis at DSBs

Mirman, Zachary; Cai, Sarah W; Lange, Titia de

doi:10.1080/15384101.2022.2123886

Cited by 14 publications

(7 citation statements)

References 69 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The most reasonable explanation is that telomerase, freed from its inhibition by CST, generates very long overhangs in POT1b KO cells. These extended overhangs may overwhelm the ability of POT1a to block ATR kinase signaling, leading to ATR- and 53BP1-dependent recruitment of CST–Polα/Primase, similar to what happens at resected DSBs or telomeres lacking both POT1a and POT1b ( Mirman et al 2018 , 2023 ; Mirman and de Lange 2020 ). This DDR-dependent loading and fill-in by CST–Polα/Primase likely mitigates C-strand loss (and dampens further ATR signaling) and thus promotes the viability of POT1b KO mice expressing telomerase.…”

Section: C-strand Maintenance By Cst–polα/primasementioning

confidence: 98%

CST–Polα/Primase: the second telomere maintenance machine

Cai

Lange

2023

Genes Dev.

Self Cite

View full text Add to dashboard Cite

It has been known for decades that telomerase extends the 3′ end of linear eukaryotic chromosomes and dictates the telomeric repeat sequence based on the template in its RNA. However, telomerase does not mitigate sequence loss at the 5′ ends of chromosomes, which results from lagging strand DNA synthesis and nucleolytic processing. Therefore, a second enzyme is needed to keep telomeres intact: DNA polymerase α/Primase bound to Ctc1–Stn1–Ten1 (CST). CST–Polα/Primase maintains telomeres through a fill-in reaction that replenishes the lost sequences at the 5′ ends. CST not only serves to maintain telomeres but also determines their length by keeping telomerase from overelongating telomeres. Here we discuss recent data on the evolution, structure, function, and recruitment of mammalian CST–Polα/Primase, highlighting the role of this complex and telomere length control in human disease.

show abstract

Section: C-strand Maintenance By Cst–polα/primasementioning

confidence: 98%

CST–Polα/Primase: the second telomere maintenance machine

Cai

Lange

2023

Genes Dev.

Self Cite

View full text Add to dashboard Cite

show abstract

“…The AF2 analysis predicted two points of interaction between shieldin and CST: SHLD1-CTC1 (Fig 1B panel vi) and SHLD2-CTC1 (Fig 1B panel v). The predicted SHLD1-CTC1 interaction has been previously described (Mirman et al, 2022a) and disrupting this interface by mutating SHLD1 leucine 20 that is buried within the binding surface ablates this interaction (Mirman et al, 2022b). Our AF2 analysis also predicts an interaction between the third SHLD2 OB-fold with CTC1 that is compatible with SHLD1-SHLD2 binding (Fig 1B panel v), though this region is not sufficient for interaction in yeast-two-hybrid assays (Mirman et al, 2018).…”

Section: Resultsmentioning

confidence: 87%

“…Shieldin is known to interact with the CST complex that facilitates fill-in of resected DNA by Polymerase α-primase (Mirman et al, 2022a). The AF2 analysis predicted two points of interaction between shieldin and CST: SHLD1-CTC1 (Fig 1B panel vi) and SHLD2-CTC1 (Fig 1B panel v).…”

Section: Resultsmentioning

confidence: 99%

An AlphaFold2 map of the 53BP1 pathway identifies a direct SHLD3-RIF1 interaction critical for DNA repair activity

Sifri

Hoeg

Durocher

et al. 2023

Preprint

View full text Add to dashboard Cite

53BP1 is a chromatin-binding DNA repair protein that promotes DNA double-strand break repair through recruitment of downstream effectors including RIF1, shieldin, and CST. The structural basis of the protein-protein interactions within the 53BP1-RIF1-shieldin-CST pathway that are essential for its DNA repair activity are largely unknown. Here we used AlphaFold2-Multimer (AF2) to predict all possible pairwise combinations of proteins within this pathway and provide structural models of seven previously characterized interactions. This analysis also predicted an entirely novel binding interface between the HEAT-repeat domain of RIF1 and the eIF4E-like domain of SHLD3. Extensive interrogation of this interface through both in vitro pulldown analysis and cellular assays supports the AF2-predicted model and demonstrates that RIF1-SHLD3 binding is essential for shieldin recruitment to sites of DNA damage, and for its role in antibody class switch recombination. Direct physical interaction between RIF1 and SHLD3 is therefore essential for 53BP1-RIF1-shieldin-CST pathway activity.

show abstract

“…Shieldin is known to interact with the CST complex that facilitates the fill‐in of resected DNA by Pol α‐Primase (Mirman et al , 2022a ). The AF2 analysis predicted two points of interaction between shieldin and CST: SHLD1‐CTC1 (Fig 1B panel vii, Appendix Fig S2 B) and SHLD2‐CTC1 (Fig 1B panel v).…”

Section: Resultsmentioning

confidence: 99%

An AlphaFold2 map of the 53BP1 pathway identifies a direct SHLD3–RIF1 interaction critical for shieldin activity

et al. 2023

View full text Add to dashboard Cite

53BP1 is a chromatin‐binding protein that promotes DNA double‐strand break repair through the recruitment of downstream effectors including RIF1, shieldin, and CST. The structural basis of the protein–protein interactions within the 53BP1‐RIF1‐shieldin‐CST pathway that are essential for its DNA repair activity is largely unknown. Here, we used AlphaFold2‐Multimer (AF2) to predict all possible pairwise combinations of proteins within this pathway and provide structural models of seven previously characterized interactions. This analysis also predicted an entirely novel binding interface between the HEAT‐repeat domain of RIF1 and the eIF4E‐like domain of SHLD3. Extensive interrogation of this interface through both in vitro pulldown analysis and cellular assays supports the AF2‐predicted model and demonstrates that RIF1‐SHLD3 binding is essential for shieldin recruitment to sites of DNA damage, and for its role in antibody class switch recombination and PARP inhibitor sensitivity. Direct physical interaction between RIF1 and SHLD3 is therefore essential for 53BP1‐RIF1‐shieldin‐CST pathway activity.

show abstract

CST/Polα/primase-mediated fill-in synthesis at DSBs

Cited by 14 publications

References 69 publications

CST–Polα/Primase: the second telomere maintenance machine

CST–Polα/Primase: the second telomere maintenance machine

An AlphaFold2 map of the 53BP1 pathway identifies a direct SHLD3-RIF1 interaction critical for DNA repair activity

An AlphaFold2 map of the 53BP1 pathway identifies a direct SHLD3–RIF1 interaction critical for shieldin activity

Contact Info

Product

Resources

About