Structures of the human CST-Polα–primase complex bound to telomere templates

He, Qixiang; Lin, Xiuhua; Chavez, Bianca L; Agrawal, Sourav; Lusk, Benjamin L; Lim, Ci Ji

doi:10.1038/s41586-022-05040-1

Cited by 57 publications

(135 citation statements)

References 62 publications

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“…Taken together, our results suggest that CST does more than simply promote binding of the DNA template to Polα-primase but also activates it for optimal primase activity. These functional conclusions are in excellent agreement with conclusions based on the recent cryo-EM structure 32 .…”

Section: Cst Activation Of Polα-primasesupporting

confidence: 90%

“…In support of this idea, the three genes for the CST components rose to the very top in CRISPR-Cas9 screens for genes important for growth of cancer cell lines with short telomeres 37 . On the basis of the work presented here, the ssDNA-binding site in the CTC1 subunit 19 or Polα-primase-binding sites in all three CST subunits 32,38 seem particularly attractive targets for interfering with telomere end replication.…”

Section: Articlementioning

confidence: 95%

“…These products may represent abortive initiation by primase 27 . Right half, the bottom of the gel containing the unincorporated 32 P-ATP was cut off to allow a longer exposure of the larger products. The 9xTEL template allowed synthesis of RNA primers of length 8 and 9 nt; size estimates have ± 1 nt uncertainty because they are based on the telomerase size markers, which have a different 5' end and different base composition.…”

Section: Reporting Summarymentioning

confidence: 99%

“…7 | Testing if DNA templates fold into G-quadruplex structures. Template DNAs were 5'-end labelled with 32 P, incubated at 30 °C in buffer containing 100 mM of the indicated salt, and then subjected to electrophoresis in a polyacrylamide gel containing 100 mM of the same salt in both the gel and the running buffer. Gels were run in a warm room at 30 °C, the same temperature as the DNA replication reactions.…”

Section: Reporting Summarymentioning

confidence: 99%

“…In each case, the RNA primer is indicated by a lighter shade and telomeric repeats are indicated by vertical bars. The location of CST relative to Polα-primase and the template DNA is taken from the recent cryo-EM structure32 . For gel source data, see Supplementary Fig.1.…”

mentioning

confidence: 99%

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Reconstitution of a telomeric replicon organized by CST

Zaug

Goodrich

Song

et al. 2022

Nature

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Telomeres, the natural ends of linear chromosomes, comprise repeat-sequence DNA and associated proteins1. Replication of telomeres allows continued proliferation of human stem cells and immortality of cancer cells2. This replication requires telomerase3 extension of the single-stranded DNA (ssDNA) of the telomeric G-strand ((TTAGGG)n); the synthesis of the complementary C-strand ((CCCTAA)n) is much less well characterized. The CST (CTC1–STN1–TEN1) protein complex, a DNA polymerase α-primase accessory factor4,5, is known to be required for telomere replication in vivo6–9, and the molecular analysis presented here reveals key features of its mechanism. We find that human CST uses its ssDNA-binding activity to specify the origins for telomeric C-strand synthesis by bound Polα-primase. CST-organized DNA polymerization can copy a telomeric DNA template that folds into G-quadruplex structures, but the challenges presented by this template probably contribute to telomere replication problems observed in vivo. Combining telomerase, a short telomeric ssDNA primer and CST–Polα–primase gives complete telomeric DNA replication, resulting in the same sort of ssDNA 3′ overhang found naturally on human telomeres. We conclude that the CST complex not only terminates telomerase extension10,11 and recruits Polα–primase to telomeric ssDNA4,12,13 but also orchestrates C-strand synthesis. Because replication of the telomere has features distinct from replication of the rest of the genome, targeting telomere-replication components including CST holds promise for cancer therapeutics.

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Section: Cst Activation Of Polα-primasesupporting

confidence: 90%