The Tetrahymena telomerase p75-p45-p19 subcomplex is a unique CST complex.
Wan B, Tang T, Upton H, Shuai J, Zhou Y, Li S, Chen J, Brunzelle J, Zeng Z, Collins K, Wu J, Lei M
Nature structural & molecular biology
2015 vol: 22 (12) pp: 1023-1026
Tetrahymena telomerase holoenzyme subunits p75, p45 and p19 form a subcomplex (7–4–1) peripheral to the catalytic core. We report structures of p45 and p19 and reveal them as the Stn1 and Ten1 subunits of the CST complex, which stimulates telomerase complementary-strand synthesis. 7–4–1 binds telomeric single-stranded DNA, and mutant p19 overexpression causes telomere 3′-overhang elongation. We propose that telomerase-tethered Tetrahymena CST coordinates telomere G-strand and C-strand synthesis.