In animals and plants, CTC1 is a component of the CST complex (consists of Ten1, Stn1 and CTC1), a complex that binds to single-stranded DNA and is required to protect telomeres from DNA degradation []. Two distinct telomere capping complexes have evolved: CST complex in budding yeast and shelterin complex in vertebrates. Budding yeast CST is composed of Cdc13, Ten1 and Stn1 []. The homologues of Ten1 and Stn1 have been identified in vertebrates and plants. The vertebrate CST complex does not appear to play a primary role in telomere protection, but may complement the function of shelterin complex []. The mammalian CST complex may have both telomeric and non-telomeric function [].In plants, the contribution of the CST components to chromosome end protection, telomeric DNA replication or both processes remains to be determined [].
In animals and plants, CTC1 is a component of the CST complex (consists of Ten1, Stn1 and CTC1), a complex that binds to single-stranded DNA and is required to protect telomeres from DNA degradation []. Two distinct telomere capping complexes have evolved: CST complex in budding yeast and shelterin complex in vertebrates. Budding yeast CST is composed of Cdc13, Ten1 and Stn1 []. The homologues of Ten1 and Stn1 have been identified in vertebrates and plants. The vertebrate CST complex does not appear to play a primary role in telomere protection, but may complement the function of shelterin complex []. The mammalian CST complex may have both telomeric and non-telomeric function [].In plants, the contribution of the CST components to chromosome end protection, telomeric DNA replication or both processes remains to be determined [].
Stn1 is a component of the CST complex, a complex that binds to single-stranded DNA and is required to protect telomeres from DNA degradation. The CST complex binds single-stranded DNA with high affinity in a sequence-independent manner, while isolated subunits bind DNA with low affinity by themselves. In addition to telomere protection, the CST complex has probably a more general role in DNA metabolism at non-telomeric sites [, ]. The C-terminal domain of Stn1 has two winged helix-turn-helix (wHTH) motifs, wHTH1 and wHTH2. This superfamily represents the wHTH1 motif, which is structurally similar to that in RPA32 with an additional large insertion between helices α2 and α3, unique to Stn1 [, ]. This additional wHTH1 motif may allow interaction with a different set of proteins that function at telomeres such as Ctc1 [].
Stn1 is a component of the CST complex, a complex that binds to single-stranded DNA and is required to protect telomeres from DNA degradation. The CST complex binds single-stranded DNA with high affinity in a sequence-independent manner, while isolated subunits bind DNA with low affinity by themselves. In addition to telomere protection, the CST complex has probably a more general role in DNA metabolism at non-telomeric sites [, ]. This entry represents the C-terminal domain of Stn1, which has two winged helix-turn-helix (wHTH) motifs, wHTH1 and wHTH2 [, ]. wHTH1 is structurally similar to that in RPA32 with an additional large insertion between helices alpha2 and alpha3, unique to Stn1, and it may allow interaction with a different set of proteins that function at telomeres such as Ctc1 []. wHTH2 is most similar to the DNA-binding wHTH motifs of the pur operon repressor and RepE replication initiator, but it does not bind double-stranded DNA [].
