| Structural highlights
Disease
[CTC1_HUMAN] Coats plus syndrome;Dyskeratosis congenita. The disease is caused by mutations affecting the gene represented in this entry.
Function
[CTC1_HUMAN] Component of the CST complex proposed to act as a specialized replication factor promoting DNA replication under conditions of replication stress or natural replication barriers such as the telomere duplex. 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. Initially the CST complex has been proposed to protect telomeres from DNA degradation (PubMed:19854130). However, the CST complex has been shown to be involved in several aspects of telomere replication. The CST complex inhibits telomerase and is involved in telomere length homeostasis; it is proposed to bind to newly telomerase-synthesized 3' overhangs and to terminate telomerase action implicating the association with the ACD:POT1 complex thus interfering with its telomerase stimulation activity. The CST complex is also proposed to be involved in fill-in synthesis of the telomeric C-strand probably implicating recruitment and activation of DNA polymerase alpha (PubMed:22763445). The CST complex facilitates recovery from many forms of exogenous DNA damage; seems to be involved in the re-initiation of DNA replication at repaired forks and/or dormant origins (PubMed:25483097). Involved in telomere maintenance (PubMed:19854131, PubMed:22863775). Involved in genome stability (PubMed:22863775). May be in involved in telomeric C-strand fill-in during late S/G2 phase (By similarity).[UniProtKB:Q5SUQ9][1] [2] [3] [4] [5]
Publication Abstract from PubMed
The human CST (Ctc1, Stn1 and Ten1) complex binds the telomeric overhang and regulates telomere length by promoting C-strand replication and inhibiting telomerase-dependent G-strand synthesis. Structural and biochemical studies on the human Stn1 and Ten1 complex revealed its mechanism of assembly and nucleic acid binding. However, little is known about the structural organization of the multi-domain Ctc1 protein and how each of these domains contribute to telomere length regulation. Here, we report the structure of a central domain of human Ctc1. The structure reveals a canonical OB-fold with the two identified disease mutations (R840W and V871M) contributing to the fold of the protein. In vitro assays suggest that although this domain is not contributing directly to Ctc1's substrate binding properties, it affects full-length Ctc1 localization to telomeres and Stn1-Ten1 binding. Moreover, functional assays show that deletion of the entire OB-fold domain leads to significant increase in telomere length, frequency of internal single G-strands and fragile telomeres. Our findings demonstrate that a previously unknown OB-fold domain contributes to efficient Ctc1 telomere localization and chromosome end maintenance.
Structural and functional analysis of an OB-fold in human Ctc1 implicated in telomere maintenance and bone marrow syndromes.,Shastrula PK, Rice CT, Wang Z, Lieberman PM, Skordalakes E Nucleic Acids Res. 2017 Dec 8. pii: 4708259. doi: 10.1093/nar/gkx1213. PMID:29228254[6]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
References
- ↑ Miyake Y, Nakamura M, Nabetani A, Shimamura S, Tamura M, Yonehara S, Saito M, Ishikawa F. RPA-like mammalian Ctc1-Stn1-Ten1 complex binds to single-stranded DNA and protects telomeres independently of the Pot1 pathway. Mol Cell. 2009 Oct 23;36(2):193-206. PMID:19854130 doi:S1097-2765(09)00587-5
- ↑ Surovtseva YV, Churikov D, Boltz KA, Song X, Lamb JC, Warrington R, Leehy K, Heacock M, Price CM, Shippen DE. Conserved telomere maintenance component 1 interacts with STN1 and maintains chromosome ends in higher eukaryotes. Mol Cell. 2009 Oct 23;36(2):207-18. PMID:19854131 doi:http://dx.doi.org/S1097-2765(09)00675-3
- ↑ Chen LY, Redon S, Lingner J. The human CST complex is a terminator of telomerase activity. Nature. 2012 Aug 23;488(7412):540-4. doi: 10.1038/nature11269. PMID:22763445 doi:http://dx.doi.org/10.1038/nature11269
- ↑ Stewart JA, Wang F, Chaiken MF, Kasbek C, Chastain PD 2nd, Wright WE, Price CM. Human CST promotes telomere duplex replication and general replication restart after fork stalling. EMBO J. 2012 Aug 29;31(17):3537-49. doi: 10.1038/emboj.2012.215. Epub 2012 Aug 3. PMID:22863775 doi:http://dx.doi.org/10.1038/emboj.2012.215
- ↑ Wang F, Stewart J, Price CM. Human CST abundance determines recovery from diverse forms of DNA damage and replication stress. Cell Cycle. 2014;13(22):3488-98. doi: 10.4161/15384101.2014.964100. PMID:25483097 doi:http://dx.doi.org/10.4161/15384101.2014.964100
- ↑ Shastrula PK, Rice CT, Wang Z, Lieberman PM, Skordalakes E. Structural and functional analysis of an OB-fold in human Ctc1 implicated in telomere maintenance and bone marrow syndromes. Nucleic Acids Res. 2017 Dec 8. pii: 4708259. doi: 10.1093/nar/gkx1213. PMID:29228254 doi:http://dx.doi.org/10.1093/nar/gkx1213
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