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 [, ].
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 and Ten1 are DNA-binding proteins with specificity for telomeric DNA substrates and both protect chromosome termini from unregulated resection and regulate telomere length. Stn1 complexes with Ten1 and Cdc13 to function as a telomere-specific replication protein A (RPA)-like complex []. These three interacting proteins associate with the telomeric overhang in budding yeast, whereas a single protein known as Pot1 (protection of telomeres-1) performs this function in fission yeast. Two separate protein complexes are required for chromosome end protection in fission yeast while a two-subunit complex consisting of POT1 and TPP1 associates with telomeric ssDNA in humans. Protection of telomeres by multiple proteins with OB-fold domains is conserved in eukaryotic evolution [].This entry represents the C-terminal domain of Stn1 and consists of tandem winged helix-turn-helix motifs [, ].
Stn1 and Ten1 are DNA-binding proteins with specificity for telomeric DNA substrates and both protect chromosome termini from unregulated resection and regulate telomere length. Stn1 complexes with Ten1 and Cdc13 to function as a telomere-specific replication protein A (RPA)-like complex []. These three interacting proteins associate with the telomeric overhang in budding yeast, whereas a single protein known as Pot1 (protection of telomeres-1) performs this function in fission yeast. Two separate protein complexes are required for chromosome end protection in fission yeast while a two-subunit complex consisting of POT1 and TPP1 associates with telomeric ssDNA in humans. Protection of telomeres by multiple proteins with OB-fold domains is conserved in eukaryotic evolution [].This entry represents the C-terminal domain of Stn1 and consists of tandem winged helix-turn-helix motifs [, ].
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 [].
The budding yeast protein Stn1 is a DNA-binding protein which has specificity for telomeric DNA. Structural profiling has predicted an OB-fold []. This entry represents the N-terminal part of the molecule, which adopts the OB fold. Protection of telomeres by multiple proteins with OB-fold domains is conserved in eukaryotic evolution [].
Stn1 and Ten1 are DNA-binding proteins with specificity for telomeric DNA substrates and both protect chromosome termini from unregulated resection and regulate telomere length []. Stn1 complexes with Ten1 and Cdc13 to function as a telomere-specific replication protein A (RPA)-like complex []. These three interacting proteins associate with the telomeric overhang in budding yeast, whereas a single protein known as Pot1 (protection of telomeres-1) performs this function in fission yeast, and a two-subunit complex consisting of POT1 and TPP1 associates with telomeric ssDNA in humans. S.pombe has Stn1- and Ten1-like proteins that are essential for chromosome end protection. Stn1 orthologues exist in all species that have Pot1, whereas Ten1-like proteins can be found in all fungi. Fission yeast Stn1 and Ten1 localise at telomeres in a manner that correlates with the length of the ssDNA overhang, suggesting that they specifically associate with the telomeric ssDNA. Two separate protein complexes are required for chromosome end protection in fission yeast. Protection of telomeres by multiple proteins with OB-fold domains is conserved in eukaryotic evolution []. Ten1 is one of the three components of the CST complex, which, in conjunction with the Shelterin complex helps protect telomeres from attack by DNA-repair mechanisms [].This entry represent Ten1 from fungi.
Cdc13 is an essential yeast protein required for telomere length regulation and genome stability. Cdc13, like a number of single-stranded telomere binding proteins, consists of several oligonucleotide-oligosaccharide binding (OB) folds. These folds potentially arise from evolutionary gene duplication and are involved in multiple functions, including nucleic acid and protein binding and Cdc13 dimerization. This entry represents the OB2 domain, second OB-fold counting from the N terminus of Cdc13. Biochemical assays indicate OB2 is not involved in telomeric DNA or Stn1 binding. However, disruption of the OB2 dimer in full-length Cdc13 affects Cdc13-Stn1 association, leading to telomere length deregulation, increased temperature sensitivity, and Stn1 binding defects. Hence it is suggested that the dimerization of the OB2 domain of Cdc13 is required for proper Cdc13, Stn1, Ten1 (CST) assembly and productive telomere capping [].
This entry represents the CST complex subunit Ten1 homologue from plants and animals []. Even though the protein sequence similarity is very low between budding yeast Ten1 () and animal/plant Ten1, they are evolutionarily related. Ten1 is essential for telomere integrity and it negatively regulates telomerase activity [].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 [].Similar to budding yeast Ten1, mammalian Ten1 forms the CST complex with Stn1 homologue and binds to single strand DNA (ssDNA). However, unlike budding yeast CST, the binding of mammalian CST to ssDNA is not sequence specific. The mammalian CST complex may have both telomeric and non-telomeric functions [].In plants, the CST complex is structurally analogous to mammalian CST and it plays a role in chromosome end protection [].
This entry contains proteins with a winged helix DNA-binding domain, including replication factor A protein 2 (RFA2) and CST complex subunit STN1.Rfa2 (also known as RPA32) is a component of the replication protein A (RPA) complex, which binds to and removes secondary structure from ssDNA. The RPA complex is involved in DNA replication, repair, and recombination []. 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 [, ].
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 [].
