CST–Polα/Primase: the second telomere maintenance machine

Cai, Sarah W; Lange, Titia de

doi:10.1101/gad.350479.123

Cited by 14 publications

(15 citation statements)

References 121 publications

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“…6c). This observation further illustrates the evolutionary kinship between the archaeal RPA and the eukaryotic CST, for which we have previously demonstrated shared features, including an AROD-like domain (Acidic Rpa1 OBbinding Domain) 22,45 and the ability to oligomerize to form supercomplexes 22,46 . We now demonstrate that they also share a similar mechanism for interacting with DNA polymerases, further establishing that archaeal RPA shares its ancestry not only with eukaryotic RPA, but also with the eukaryotic CST telomere maintenance complex.…”

Section: Prisl Binds To Rpa2 Wh Via a Canonical Wh Interfacesupporting

confidence: 73%

Communication between DNA polymerases and Replication Protein A within the archaeal replisome

Martínez-Carranza,

Vialle,

Madru

et al. 2024

Preprint

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Replication Protein A (RPA) plays a pivotal role in DNA replication by coating and protecting exposed single-stranded DNA, and acting as a molecular hub that recruits additional replication factors. We demonstrated that archaeal RPA hosts a winged-helix domain (WH) that interacts with two key actors of the replisome: the DNA primase (PriSL) and the replicative DNA polymerase (PolD). Using an integrative structural biology approach, combining nuclear magnetic resonance, X-ray crystallography and cryo-electron microscopy, we unveiled how RPA interacts with PriSL and PolD through two distinct surfaces of the WH domain: an evolutionarily conserved interface and a novel binding site. Finally, RPA was shown to stimulate the activity of PriSL in a WH-dependent manner. This study provides a molecular understanding of the WH-mediated regulatory activity in conserved central replication factors such as RPA, which regulate genome maintenance in Archaea and Eukaryotes.

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Section: Prisl Binds To Rpa2 Wh Via a Canonical Wh Interfacesupporting

confidence: 73%

Communication between DNA polymerases and Replication Protein A within the archaeal replisome

Martínez-Carranza,

Vialle,

Madru

et al. 2024

Preprint

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“…In keeping with the critical role of CST–Polα-primase in solving the second end-replication problem, defects in this pathway lead to telomere biology disorders –predominantly Coats plus and, more rarely, dyskeratosis congenita– (reviewed in refs. 21 and 40 21,40 ). It was proposed that CST– Polα-primase evolved in LECA (or its Asgard archaeal ancestor) to maintain the 5ʹ ends of linear chromosomes 21,25 .…”

Section: Mainmentioning

confidence: 96%

“…21 and 40 21,40 ). It was proposed that CST– Polα-primase evolved in LECA (or its Asgard archaeal ancestor) to maintain the 5ʹ ends of linear chromosomes 21,25 . Our data argue for this view since the lagging-strand end-replication problem likely threatened the maintenance of the first linear chromosomes.…”

Section: Mainmentioning

confidence: 96%

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CST–Polymeraseα-primase solves a second telomere end-replication problem

Takai,

Aria,

Borges

et al. 2023

Preprint

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Telomerase solves the end–replication problem by adding G–rich telomeric repeats to the 3′ ends of telomeres1. We report a second end–replication problem affecting the C–rich telomeric repeat strand that is solved by fill–in synthesis by CST—Polymeraseα(Polα)–primase. In vitro replication of linear DNAs showed that lagging–strand DNA synthesis stops >40 nt before the replisome reaches the 5′ end of the template. Incomplete lagging–strand DNA synthesis is predicted to result in progressive shortening of the telomeric C–strand. Two assays to measure C–strand shortening at telomere ends in telomerase–deficient cells lacking the Ctc1 subunit of CST—Polα–primase revealed that lagging–end telomeres lose C–strand sequences at ~60 nt/population doubling (PD), consistent with the in vitro replication data. The C–strands of leading–end telomeres shortened by ~108 nt/PD, consistent with resection converting the blunt ends to 3′ overhangs. The overall shortening rate of the C–rich telomeric strand in Ctc1–deficient cells was consistent with the combined effects of incomplete lagging–strand synthesis and 5′ end resection at the leading–ends. We conclude that canonical DNA replication creates two telomere end–replication problems that require telomerase to maintain the G–rich strand and CST—Polα–primase to maintain the C–rich strand.

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“…The CST (CTC1/STN1/TEN1)-PP (Primase/DNA polymerase alpha) complex plays a crucial role in the C-strand fill-in processes at telomeres (62). It recognizes exposed Grich strands, including higher-order structures like as G-quadruplex, on the parental lagging strand during telomere replication and initiates the filling in of the complementary C-strand, generating additional Okazaki fragments that serve to remove the gaps in the lagging strand and ensure the telomere replication (63)(64)(65)(66)(67).…”

Section: Cst Complex-mediated Priming and Subsequent Strand Displacem...mentioning

confidence: 99%

Extrachromosomal Telomeres Derived from Excessive Strand Displacements

Lee

Sohn

et al. 2023

Preprint

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Alternative Lengthening of Telomeres (ALT) is a telomere maintenance mechanism mediated by break-induced replication (BIR), evident in approximately 15% of human cancers. A characteristic feature of ALT cancers is the presence of C-circles, circular single-stranded telomeric DNAs composed of C-rich sequences. Despite the fact that extrachromosomal C-rich single-stranded DNAs (ssDNAs), unique to ALT cells, are considered potential precursors of C-circles, their generation process remains undefined. Here, we introduce a highly sensitive method to detect single stranded telomeric DNA, called 4SET (Strand-Specific Southern-blot for Single-stranded Extrachromosomal Telomeres) assay. Utilizing 4SET, we are able to capture C-rich single stranded DNAs are near 500 bp in size. Both C-rich ssDNAs and C-circles are abundant in cytoplasmic fraction which supports the idea that C-rich ssDNAs may indeed precede C-circles. We also found that C-rich ssDNAs originate during Okazaki fragment processing in lagging strands. The generation of C-rich ssDNA requires CST-PP (CTC1/STN1/TEN1-PRIMASE-Polymerase alpha)-complex mediated priming of the C-strand synthesis and subsequent excessive strand displacement of C-rich strand through DNA Polymerase delta and BLM helicase. Our work proposes a new model for the generation of C-rich ssDNAs and C-circles that are indicative of the presence of ALT pathway.

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CST–Polα/Primase: the second telomere maintenance machine

Cited by 14 publications

References 121 publications

Communication between DNA polymerases and Replication Protein A within the archaeal replisome

Communication between DNA polymerases and Replication Protein A within the archaeal replisome

CST–Polymeraseα-primase solves a second telomere end-replication problem

Extrachromosomal Telomeres Derived from Excessive Strand Displacements

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