7uy7

Tetrahymena CST with Polymerase alpha-PrimaseTetrahymena CST with Polymerase alpha-Primase

Structural highlights 7uy7 is a 6 chain structure with sequence from Tetrahymena thermophila. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Ligands: Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function [TAP19_TETTS] Component of a CST-like subcomplex of the holoenzyme telomerase ribonucleoprotein complex, which stimulates telomerase complementary-strand synthesis (PubMed:26551074). Telomerase is an essential ribonucleoprotein enzyme that copies new telomeric repeats onto chromosome ends by repetitively synthesizing the short telomere-repeat sequence 5'-TTGGGG-3' using an RNA template component TER (PubMed:26551074). The CST-like subcomplex (also named 7-4-1) binds telomeric single-stranded DNA and coordinates telomere G-strand and C-strand synthesis (PubMed:26551074). Publication Abstract from PubMed Telomeres are the physical ends of linear chromosomes. They are composed of short repeating sequences (such as TTGGGG in the G-strand for Tetrahymena thermophila) of double-stranded DNA with a single-strand 3' overhang of the G-strand and, in humans, the six shelterin proteins: TPP1, POT1, TRF1, TRF2, RAP1 and TIN2(1,2). TPP1 and POT1 associate with the 3' overhang, with POT1 binding the G-strand(3) and TPP1 (in complex with TIN2(4)) recruiting telomerase via interaction with telomerase reverse transcriptase(5) (TERT). The telomere DNA ends are replicated and maintained by telomerase(6), for the G-strand, and subsequently DNA polymerase alpha-primase(7,8) (PolalphaPrim), for the C-strand(9). PolalphaPrim activity is stimulated by the heterotrimeric complex CTC1-STN1-TEN1(10-12) (CST), but the structural basis of the recruitment of PolalphaPrim and CST to telomere ends remains unknown. Here we report cryo-electron microscopy (cryo-EM) structures of Tetrahymena CST in the context of the telomerase holoenzyme, in both the absence and the presence of PolalphaPrim, and of PolalphaPrim alone. Tetrahymena Ctc1 binds telomerase subunit p50, a TPP1 orthologue, on a flexible Ctc1 binding motif revealed by cryo-EM and NMR spectroscopy. The PolalphaPrim polymerase subunit POLA1 binds Ctc1 and Stn1, and its interface with Ctc1 forms an entry port for G-strand DNA to the POLA1 active site. We thus provide a snapshot of four key components that are required for telomeric DNA synthesis in a single active complex-telomerase-core ribonucleoprotein, p50, CST and PolalphaPrim-that provides insights into the recruitment of CST and PolalphaPrim and the handoff between G-strand and C-strand synthesis. Structure of Tetrahymena telomerase-bound CST with polymerase alpha-primase.,He Y, Song H, Chan H, Liu B, Wang Y, Susac L, Zhou ZH, Feigon J Nature. 2022 Aug;608(7924):813-818. doi: 10.1038/s41586-022-04931-7. Epub 2022, Jul 13. PMID:35831498 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

spinqualitylabelsall models 7uy7, resolution 4.20Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image