Biology:CST complex
The CST complex is a cellular multiprotein complex involved in telomere maintenance. In budding yeast (Saccharomyces cerevisiae), it is composed of the proteins Cdc13, Stn1, and Ten1; in mammals, it consists of the proteins CTC1, STN1, and TEN1.[1] It is related to the replication protein A complex.
Structure
 | This section is missing information about Resolved structures of yeast and human CST; different stoichiometry and human CST similarity to RPA. (December 2020) |
For budding yeast as well as for mammals, CST is a protein heterotrimer, consisting of three distinct proteins. Yeast Stn1 and Ten1 are orthologous proteins to mammalian STN1 and TEN1.[1][2] But yeast Cdc13 and mammalian CTC1 are very different in amino acid sequence, length, and to some extent in function.[3][4]
Function
For both budding yeast and mammals, the CST complex contributes to telomere maintenance, but this function is more crucial for budding yeast, where the CST complex performs the functions that shelterin performs in vertebrates.[1] At least four factors contribute to telomere maintenance: telomerase, shelterin, TERRA and the CST Complex.[5] CST protection of telomeres for mammals occurs under conditions of replication stress. But when not replicating DNA, mammals primarily require shelterin for telomere protection.[6] T-loops and G-quadruplexes are described as the two tertiary DNA structures that protect telomere ends and regulate telomere length.[3] In fungus, the CST complex has been shown to unfold higher order G-tailed structures, such as occur with telomere exposure during DNA replication.[7]
See also
References
- ↑ 1.0 1.1 1.2 "Evolution of CST function in telomere maintenance". Cell Cycle 9 (16): 3157–65. August 2010. doi:10.4161/cc.9.16.12547. PMID 20697207.
- ↑ "Stn1-Ten1 is an Rpa2-Rpa3-like complex at telomeres". Genes & Development 23 (24): 2900–14. December 2009. doi:10.1101/gad.1851909. PMID 20008938.
- ↑ 3.0 3.1 "Structure and function of the telomeric CST complex". Computational and Structural Biotechnology Journal 14: 161–7. 2016. doi:10.1016/j.csbj.2016.04.002. PMID 27239262.
- ↑ "Analyses of Candida Cdc13 orthologues revealed a novel OB fold dimer arrangement, dimerization-assisted DNA binding, and substantial structural differences between Cdc13 and RPA70". Molecular and Cellular Biology 32 (1): 186–98. January 2012. doi:10.1128/MCB.05875-11. PMID 22025677.
- ↑ "CST meets shelterin to keep telomeres in check". Molecular Cell 39 (5): 665–76. September 2010. doi:10.1016/j.molcel.2010.08.024. PMID 20832719.
- ↑ "Human CST promotes telomere duplex replication and general replication restart after fork stalling". The EMBO Journal 31 (17): 3537–49. August 2012. doi:10.1038/emboj.2012.215. PMID 22863775.
- ↑ "The telomere capping complex CST has an unusual stoichiometry, makes multipartite interaction with G-Tails, and unfolds higher-order G-tail structures". PLOS Genetics 9 (1): e1003145. 2013. doi:10.1371/journal.pgen.1003145. PMID 23300477.
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