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Vaquero-Sedas MI, Vega-Palas MA. A Nested PCR Telomere Fusion Assay Highlights the Widespread End-Capping Protection of Arabidopsis CTC1. Int J Mol Sci 2024; 25:672. [PMID: 38203842 PMCID: PMC10779545 DOI: 10.3390/ijms25010672] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2023] [Revised: 11/15/2023] [Accepted: 11/18/2023] [Indexed: 01/12/2024] Open
Abstract
Telomeres protect the ends of linear eukaryotic chromosomes from being recognized as DNA double-strand breaks. Two major protein complexes are involved in the protection of telomeres: shelterin and CST. The dysfunction of these complexes can challenge the function of telomeres and lead to telomere fusions, breakage-fusion-bridge cycles, and cell death. Therefore, monitoring telomere fusions helps to understand telomeres biology. Telomere fusions are often analyzed by Fluorescent In Situ Hybridization (FISH) or PCR. Usually, both methods involve hybridization with a telomeric probe, which allows the detection of fusions containing telomeric sequences, but not of those lacking them. With the aim of detecting both types of fusion events, we have developed a nested PCR method to analyze telomere fusions in Arabidopsis thaliana. This method is simple, accurate, and does not require hybridization. We have used it to analyze telomere fusions in wild-type and mutant plants altered in CTC1, one of the three components of the Arabidopsis CST telomere capping complex. Our results show that null ctc1-2 mutant plants display fusions between all telomeric regions present in Arabidopsis chromosomes 1, 3 and 5, thus highlighting the widespread end-capping protection achieved by CTC1.
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Affiliation(s)
| | - Miguel A. Vega-Palas
- Instituto de Bioquímica Vegetal y Fotosíntesis, CSIC-Universidad de Sevilla, IBVF (CSIC-US), E41092 Seville, Spain;
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2
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Luo M, Teng X, Wang B, Zhang J, Liu Y, Liu D, Li H, Lu H. Protection of telomeres 1 (POT1) of Pinus tabuliformis bound the telomere ssDNA. TREE PHYSIOLOGY 2020; 40:119-127. [PMID: 31860719 DOI: 10.1093/treephys/tpz125] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/27/2019] [Revised: 10/14/2019] [Accepted: 11/15/2019] [Indexed: 06/10/2023]
Abstract
Protection of telomeres 1 (POT1) is a telomeric protein that binds to the telomere single-stranded (ss) region. It plays an essential role in maintaining genomic stability in both plants and animals. In this study, we investigated the properties of POT1 in Pinus tabuliformis Carr. (PtPOT1) through electrophoretic mobility shift assay. PtPOT1 harbored affinity for telomeric ssDNA and could bind plant- and mammalian-type ssDNA sequences. Notably, there were two oligonucleotide/oligosaccharide binding (OB) folds, and OB1 or OB2 alone, or both together, could bind ssDNA, which is significantly different from human POT1. Based on our data, we hypothesized that the two OB folds of PtPOT1 bound the same ssDNA. This model not only provides new insight into the ssDNA binding of PtPOT1 but also sheds light on the functional divergence of POT1 proteins in gymnosperms and humans.
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Affiliation(s)
- Mei Luo
- Beijing Advanced Innovation Center for Tree Breeding by Molecular Design, Beijing Forestry University, No.35, Qinghua East road, Haidian District, Beijing 100083, China
- College of Biological Sciences and Biotechnology, Beijing Forestry University, Beijing 100083, China
| | - Xiaotong Teng
- College of Biological Sciences and Biotechnology, Beijing Forestry University, Beijing 100083, China
| | - Bing Wang
- College of Biological Sciences and Biotechnology, Beijing Forestry University, Beijing 100083, China
| | - Jiaxue Zhang
- College of Biological Sciences and Biotechnology, Beijing Forestry University, Beijing 100083, China
| | - Yadi Liu
- College of Biological Sciences and Biotechnology, Beijing Forestry University, Beijing 100083, China
| | - Di Liu
- College of Biological Sciences and Biotechnology, Beijing Forestry University, Beijing 100083, China
| | - Hui Li
- College of Biological Sciences and Biotechnology, Beijing Forestry University, Beijing 100083, China
| | - Hai Lu
- Beijing Advanced Innovation Center for Tree Breeding by Molecular Design, Beijing Forestry University, No.35, Qinghua East road, Haidian District, Beijing 100083, China
- College of Biological Sciences and Biotechnology, Beijing Forestry University, Beijing 100083, China
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3
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Barbero Barcenilla B, Shippen DE. Back to the future: The intimate and evolving connection between telomere-related factors and genotoxic stress. J Biol Chem 2019; 294:14803-14813. [PMID: 31434740 DOI: 10.1074/jbc.aw119.008145] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
The conversion of circular genomes to linear chromosomes during molecular evolution required the invention of telomeres. This entailed the acquisition of factors necessary to fulfill two new requirements: the need to fully replicate terminal DNA sequences and the ability to distinguish chromosome ends from damaged DNA. Here we consider the multifaceted functions of factors recruited to perpetuate and stabilize telomeres. We discuss recent theories for how telomere factors evolved from existing cellular machineries and examine their engagement in nontelomeric functions such as DNA repair, replication, and transcriptional regulation. We highlight the remarkable versatility of protection of telomeres 1 (POT1) proteins that was fueled by gene duplication and divergence events that occurred independently across several eukaryotic lineages. Finally, we consider the relationship between oxidative stress and telomeres and the enigmatic role of telomere-associated proteins in mitochondria. These findings point to an evolving and intimate connection between telomeres and cellular physiology and the strong drive to maintain chromosome integrity.
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Affiliation(s)
- Borja Barbero Barcenilla
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, Texas 77843-2128
| | - Dorothy E Shippen
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, Texas 77843-2128
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4
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Arora A, Beilstein MA, Shippen DE. Evolution of Arabidopsis protection of telomeres 1 alters nucleic acid recognition and telomerase regulation. Nucleic Acids Res 2016; 44:9821-9830. [PMID: 27651456 PMCID: PMC5175356 DOI: 10.1093/nar/gkw807] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2016] [Revised: 09/01/2016] [Accepted: 09/03/2016] [Indexed: 11/14/2022] Open
Abstract
Protection of telomeres (POT1) binds chromosome ends, recognizing single-strand telomeric DNA via two oligonucleotide/oligosaccharide binding folds (OB-folds). The Arabidopsis thaliana POT1a and POT1b paralogs are atypical: they do not exhibit telomeric DNA binding, and they have opposing roles in regulating telomerase activity. AtPOT1a stimulates repeat addition processivity of the canonical telomerase enzyme, while AtPOT1b interacts with a regulatory lncRNA that represses telomerase activity. Here, we show that OB1 of POT1a, but not POT1b, has an intrinsic affinity for telomeric DNA. DNA binding was dependent upon a highly conserved Phe residue (F65) that in human POT1 directly contacts telomeric DNA. F65A mutation of POT1aOB1 abolished DNA binding and diminished telomerase repeat addition processivity. Conversely, AtPOT1b and other POT1b homologs from Brassicaceae and its sister family, Cleomaceae, naturally bear a non-aromatic amino acid at this position. By swapping Val (V63) with Phe, AtPOT1bOB1 gained the capacity to bind telomeric DNA and to stimulate telomerase repeat addition processivity. We conclude that, in the context of DNA binding, variation at a single amino acid position promotes divergence of the AtPOT1b paralog from the ancestral POT1 protein.
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Affiliation(s)
- Amit Arora
- Department of Biochemistry and Biophysics, Texas A&M University, 2128 TAMU, College Station, TX 77843, USA
| | - Mark A Beilstein
- School of Plant Sciences, University of Arizona, Tucson, AZ 85721, USA
| | - Dorothy E Shippen
- Department of Biochemistry and Biophysics, Texas A&M University, 2128 TAMU, College Station, TX 77843, USA
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5
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Procházková Schrumpfová P, Schořová Š, Fajkus J. Telomere- and Telomerase-Associated Proteins and Their Functions in the Plant Cell. FRONTIERS IN PLANT SCIENCE 2016; 7:851. [PMID: 27446102 PMCID: PMC4924339 DOI: 10.3389/fpls.2016.00851] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/12/2015] [Accepted: 05/31/2016] [Indexed: 05/20/2023]
Abstract
Telomeres, as physical ends of linear chromosomes, are targets of a number of specific proteins, including primarily telomerase reverse transcriptase. Access of proteins to the telomere may be affected by a number of diverse factors, e.g., protein interaction partners, local DNA or chromatin structures, subcellular localization/trafficking, or simply protein modification. Knowledge of composition of the functional nucleoprotein complex of plant telomeres is only fragmentary. Moreover, the plant telomeric repeat binding proteins that were characterized recently appear to also be involved in non-telomeric processes, e.g., ribosome biogenesis. This interesting finding was not totally unexpected since non-telomeric functions of yeast or animal telomeric proteins, as well as of telomerase subunits, have been reported for almost a decade. Here we summarize known facts about the architecture of plant telomeres and compare them with the well-described composition of telomeres in other organisms.
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Affiliation(s)
- Petra Procházková Schrumpfová
- Mendel Centre for Plant Genomics and Proteomics, Central European Institute of Technology, Masaryk UniversityBrno, Czech Republic
- Laboratory of Functional Genomics and Proteomics, National Centre for Biomolecular Research, Faculty of Science, Masaryk UniversityBrno, Czech Republic
- *Correspondence: Petra Procházková Schrumpfová,
| | - Šárka Schořová
- Laboratory of Functional Genomics and Proteomics, National Centre for Biomolecular Research, Faculty of Science, Masaryk UniversityBrno, Czech Republic
| | - Jiří Fajkus
- Mendel Centre for Plant Genomics and Proteomics, Central European Institute of Technology, Masaryk UniversityBrno, Czech Republic
- Laboratory of Functional Genomics and Proteomics, National Centre for Biomolecular Research, Faculty of Science, Masaryk UniversityBrno, Czech Republic
- Institute of Biophysics, Academy of Sciences of the Czech Republic, v.v.i.Brno, Czech Republic
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6
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Beilstein MA, Renfrew KB, Song X, Shakirov EV, Zanis MJ, Shippen DE. Evolution of the Telomere-Associated Protein POT1a in Arabidopsis thaliana Is Characterized by Positive Selection to Reinforce Protein-Protein Interaction. Mol Biol Evol 2015; 32:1329-41. [PMID: 25697340 DOI: 10.1093/molbev/msv025] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
Gene duplication is a major driving force in genome evolution. Here, we explore the nature and origin of the POT1 gene duplication in Arabidopsis thaliana. Protection of Telomeres (POT1) is a conserved multifunctional protein that modulates telomerase activity and its engagement with telomeres. Arabidopsis thaliana encodes two divergent POT1 paralogs termed AtPOT1a and AtPOT1b. AtPOT1a positively regulates telomerase activity, whereas AtPOT1b is proposed to negatively regulate telomerase and promote chromosome end protection. Phylogenetic analysis uncovered two independent POT1 duplication events in the plant kingdom, including one at the base of Brassicaceae. Tests for positive selection implemented in PAML revealed that the Brassicaceae POT1a lineage experienced positive selection postduplication and identified three amino acid residues with signatures of positive selection. A sensitive and quantitative genetic complementation assay was developed to assess POT1a function in A. thaliana. The assay showed that AtPOT1a is functionally distinct from single-copy POT1 genes in other plants. Moreover, for two of the sites with a strong signature of positive selection, substitutions that swap the amino acids in AtPOT1a for residues found in AtPOT1b dramatically compromised AtPOT1a function in vivo. In vitro-binding studies demonstrated that all three sites under positive selection specifically enhance the AtPOT1a interaction with CTC1, a core component of the highly conserved CST (CTC1/STN1/TEN1) telomere protein complex. Our results reveal a molecular mechanism for the role of these positively selected sites in AtPOT1a. The data also provide an important empirical example to refine theories of duplicate gene retention, as the outcome of positive selection here appears to be reinforcement of an ancestral function, rather than neofunctionalization. We propose that this outcome may not be unusual when the duplicated protein is a component of a multisubunit complex whose function is in part specified by other members.
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Affiliation(s)
- Mark A Beilstein
- School of Plant Sciences, University of Arizona Department of Biochemistry and Biophysics, Texas A&M University
| | - Kyle B Renfrew
- Department of Biochemistry and Biophysics, Texas A&M University
| | - Xiangyu Song
- Department of Biochemistry and Biophysics, Texas A&M University
| | - Eugene V Shakirov
- Department of Integrative Biology, University of Texas at Austin Institute of Fundamental Medicine and Biology, Kazan (Volga Region) Federal University, Kazan, Republic of Tatarstan, Russia
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7
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Amiard S, Olivier M, Allain E, Choi K, Smith-Unna R, Henderson IR, White CI, Gallego ME. Telomere stability and development of ctc1 mutants are rescued by inhibition of EJ recombination pathways in a telomerase-dependent manner. Nucleic Acids Res 2014; 42:11979-91. [PMID: 25274733 PMCID: PMC4231758 DOI: 10.1093/nar/gku897] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2014] [Revised: 09/16/2014] [Accepted: 09/18/2014] [Indexed: 12/11/2022] Open
Abstract
The telomeres of linear eukaryotic chromosomes are protected by caps consisting of evolutionarily conserved nucleoprotein complexes. Telomere dysfunction leads to recombination of chromosome ends and this can result in fusions which initiate chromosomal breakage-fusion-bridge cycles, causing genomic instability and potentially cell death or cancer. We hypothesize that in the absence of the recombination pathways implicated in these fusions, deprotected chromosome ends will instead be eroded by nucleases, also leading to the loss of genes and cell death. In this work, we set out to specifically test this hypothesis in the plant, Arabidopsis. Telomere protection in Arabidopsis implicates KU and CST and their absence leads to chromosome fusions, severe genomic instability and dramatic developmental defects. We have analysed the involvement of end-joining recombination pathways in telomere fusions and the consequences of this on genomic instability and growth. Strikingly, the absence of the multiple end-joining pathways eliminates chromosome fusion and restores normal growth and development to cst ku80 mutant plants. It is thus the chromosomal fusions, per se, which are the underlying cause of the severe developmental defects. This rescue is mediated by telomerase-dependent telomere extension, revealing a competition between telomerase and end-joining recombination proteins for access to deprotected telomeres.
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Affiliation(s)
- Simon Amiard
- Génétique, Reproduction et Développement, UMR CNRS 6293, Clermont Université, INSERM U1103, Aubière, France
| | - Margaux Olivier
- Génétique, Reproduction et Développement, UMR CNRS 6293, Clermont Université, INSERM U1103, Aubière, France
| | - Elisabeth Allain
- Génétique, Reproduction et Développement, UMR CNRS 6293, Clermont Université, INSERM U1103, Aubière, France Department of Plant Sciences, University of Cambridge, Cambridge, UK
| | - Kyuha Choi
- Department of Plant Sciences, University of Cambridge, Cambridge, UK
| | | | - Ian R Henderson
- Department of Plant Sciences, University of Cambridge, Cambridge, UK
| | - Charles I White
- Génétique, Reproduction et Développement, UMR CNRS 6293, Clermont Université, INSERM U1103, Aubière, France
| | - Maria Eugenia Gallego
- Génétique, Reproduction et Développement, UMR CNRS 6293, Clermont Université, INSERM U1103, Aubière, France
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8
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Lee YW, Kim WT. Telomerase-dependent 3' G-strand overhang maintenance facilitates GTBP1-mediated telomere protection from misplaced homologous recombination. THE PLANT CELL 2013; 25:1329-42. [PMID: 23572544 PMCID: PMC3663271 DOI: 10.1105/tpc.112.107573] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/19/2012] [Revised: 02/17/2013] [Accepted: 03/26/2013] [Indexed: 05/09/2023]
Abstract
At the 3'-end of telomeres, single-stranded G-overhang telomeric repeats form a stable T-loop. Many studies have focused on the mechanisms that generate and regulate the length of telomere 3' G-strand overhangs, but the roles of G-strand overhang length control in proper T-loop formation and end protection remain unclear. Here, we examined functional relationships between the single-stranded telomere binding protein GTBP1 and G-strand overhang lengths maintained by telomerase in tobacco (Nicotiana tabacum). In tobacco plants, telomerase reverse transcriptase subunit (TERT) repression severely worsened the GTBP1 knockdown phenotypes, which were formally characterized as an outcome of telomere destabilization. TERT downregulation shortened the telomere 3' G-overhangs and increased telomere recombinational aberrations in GTBP1-suppressed plants. Correlatively, GTBP1-mediated inhibition of single-strand invasion into the double-strand telomeric sequences was impaired due to shorter single-stranded telomeres. Moreover, TERT/GTBP1 double knockdown amplified misplaced homologous recombination of G-strand overhangs into intertelomeric regions. Thus, proper G-overhang length maintenance is required to protect telomeres against intertelomeric recombination, which is achieved by the balanced functions of GTBP1 and telomerase activity.
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Affiliation(s)
- Yong Woo Lee
- Department of Systems Biology, College of Life Science and Biotechnology, Yonsei University, Seoul 120-749, Korea
| | - Woo Taek Kim
- Department of Systems Biology, College of Life Science and Biotechnology, Yonsei University, Seoul 120-749, Korea
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9
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Nelson ADL, Shippen DE. Surprises from the chromosome front: lessons from Arabidopsis on telomeres and telomerase. COLD SPRING HARBOR SYMPOSIA ON QUANTITATIVE BIOLOGY 2013; 77:7-15. [PMID: 23460576 DOI: 10.1101/sqb.2013.77.017053] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Telomeres serve two vital functions: They act as a buffer against the end-replication problem, and they prevent chromosome ends from being recognized as double-strand DNA (dsDNA) breaks. These functions are orchestrated by the telomerase reverse transcriptase and a variety of telomere protein complexes. Here, we discuss our recent studies with Arabidopsis thaliana that uncovered a new and highly conserved telomere complex called CST (Cdc13/CTC1, STN1, TEN1). Formerly believed to be yeast specific, CST has now been identified as a key component of both plant and vertebrate telomeres, which is essential for genome integrity and stem cell viability. We also describe the unexpected discovery of alternative telomerase ribonucleoprotein complexes in Arabidopsis. Fueled by duplication and diversification of the telomerase RNA subunit and telomerase accessory proteins, these telomerase complexes act in concert to maintain genome stability. In addition to the canonical telomerase enzyme, one of two alternative telomerase ribonucleoprotein (RNP) complexes functions as a novel negative regulator of enzyme activity in response to genotoxic stress. These contributions highlight the immense potential of Arabidopsis in probing the depths of the chromosome end.
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Affiliation(s)
- A D L Nelson
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, Texas 77843-2128, USA
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10
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An alternative telomerase RNA in Arabidopsis modulates enzyme activity in response to DNA damage. Genes Dev 2012; 26:2512-23. [PMID: 23109676 DOI: 10.1101/gad.202960.112] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
Telomerase replenishes telomere tracts by reiteratively copying its RNA template, TER. Unlike other model organisms, Arabidopsis thaliana harbors two divergent TER genes. However, only TER1 is required for telomere maintenance. Here we examine the function of TER2. We show that TER2 is spliced and its 3' end is truncated in vivo to generate a third TER isoform, TER2(S). TERT preferentially associates with TER2 > TER1 > TER2(S). Moreover, TER2 and TER2(S) assemble with Ku and POT1b (protection of telomeres), forming RNP (ribonucleoprotein) complexes distinct from TER1 RNP. Plants null for TER2 display increased telomerase enzyme activity, while TER2 overexpression inhibits telomere synthesis from TER1 and leads to telomere shortening. These findings argue that TER2 negatively regulates telomerase by sequestering TERT in a nonproductive RNP complex. Introduction of DNA double-strand breaks by zeocin leads to an immediate and specific spike in TER2 and a concomitant decrease in telomerase enzyme activity. This response is not triggered by replication stress or telomere dysfunction and is abrogated in ter2 mutants. We conclude that Arabidopsis telomerase is modulated by TER2, a novel DNA damage-induced noncoding RNA that works in concert with the canonical TER to promote genome integrity.
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11
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Lee LY, Wu FH, Hsu CT, Shen SC, Yeh HY, Liao DC, Fang MJ, Liu NT, Yen YC, Dokládal L, Sýkorová E, Gelvin SB, Lin CS. Screening a cDNA library for protein-protein interactions directly in planta. THE PLANT CELL 2012; 24:1746-59. [PMID: 22623495 PMCID: PMC3442567 DOI: 10.1105/tpc.112.097998] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/09/2012] [Revised: 04/25/2012] [Accepted: 05/02/2012] [Indexed: 05/18/2023]
Abstract
Screening cDNA libraries for genes encoding proteins that interact with a bait protein is usually performed in yeast. However, subcellular compartmentation and protein modification may differ in yeast and plant cells, resulting in misidentification of protein partners. We used bimolecular fluorescence complementation technology to screen a plant cDNA library against a bait protein directly in plants. As proof of concept, we used the N-terminal fragment of yellow fluorescent protein- or nVenus-tagged Agrobacterium tumefaciens VirE2 and VirD2 proteins and the C-terminal extension (CTE) domain of Arabidopsis thaliana telomerase reverse transcriptase as baits to screen an Arabidopsis cDNA library encoding proteins tagged with the C-terminal fragment of yellow fluorescent protein. A library of colonies representing ~2 × 10(5) cDNAs was arrayed in 384-well plates. DNA was isolated from pools of 10 plates, individual plates, and individual rows and columns of the plates. Sequential screening of subsets of cDNAs in Arabidopsis leaf or tobacco (Nicotiana tabacum) Bright Yellow-2 protoplasts identified single cDNA clones encoding proteins that interact with either, or both, of the Agrobacterium bait proteins, or with CTE. T-DNA insertions in the genes represented by some cDNAs revealed five novel Arabidopsis proteins important for Agrobacterium-mediated plant transformation. We also used this cDNA library to confirm VirE2-interacting proteins in orchid (Phalaenopsis amabilis) flowers. Thus, this technology can be applied to several plant species.
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Affiliation(s)
- Lan-Ying Lee
- Department of Biological Sciences, Purdue University, West Lafayette, Indiana 47907-1392
| | - Fu-Hui Wu
- Agricultural Biotechnology Research Center, Academia Sinica, Taipei 115, Taiwan
| | - Chen-Tran Hsu
- Agricultural Biotechnology Research Center, Academia Sinica, Taipei 115, Taiwan
| | - Shu-Chen Shen
- Scientific Instrument Center, Academia Sinica, Taipei 115, Taiwan
| | - Hsuan-Yu Yeh
- Agricultural Biotechnology Research Center, Academia Sinica, Taipei 115, Taiwan
| | - De-Chih Liao
- Agricultural Biotechnology Research Center, Academia Sinica, Taipei 115, Taiwan
| | - Mei-Jane Fang
- Core Facilities, Institute of Plant and Microbial Biology, Academia Sinica, Taipei 115, Taiwan
| | - Nien-Tze Liu
- Agricultural Biotechnology Research Center, Academia Sinica, Taipei 115, Taiwan
| | - Yu-Chen Yen
- Department of Biological Sciences, Purdue University, West Lafayette, Indiana 47907-1392
| | - Ladislav Dokládal
- Institute of Biophysics, Academy of Sciences of the Czech Republic, 612 65 Brno, Czech Republic
- Central European Institute of Technology, Masaryk University, 625 00 Brno, Czech Republic
| | - Eva Sýkorová
- Institute of Biophysics, Academy of Sciences of the Czech Republic, 612 65 Brno, Czech Republic
- Central European Institute of Technology, Masaryk University, 625 00 Brno, Czech Republic
| | - Stanton B. Gelvin
- Department of Biological Sciences, Purdue University, West Lafayette, Indiana 47907-1392
| | - Choun-Sea Lin
- Agricultural Biotechnology Research Center, Academia Sinica, Taipei 115, Taiwan
- Address correspondence to
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12
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Shakirov EV, Shippen DE. Selaginella moellendorffii telomeres: conserved and unique features in an ancient land plant lineage. FRONTIERS IN PLANT SCIENCE 2012; 3:161. [PMID: 22833748 PMCID: PMC3400083 DOI: 10.3389/fpls.2012.00161] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/16/2012] [Accepted: 06/29/2012] [Indexed: 05/07/2023]
Abstract
Telomeres, the essential terminal regions of linear eukaryotic chromosomes, consist of G-rich DNA repeats bound by a plethora of associated proteins. While the general pathways of telomere maintenance are evolutionarily conserved, individual telomere complex components show remarkable variation between eukaryotic lineages and even within closely related species. The recent genome sequencing of the lycophyte Selaginella moellendorffii and the availability of an ever-increasing number of flowering plant genomes provides a unique opportunity to evaluate the molecular and functional evolution of telomere components from the early evolving non-seed plants to the more developmentally advanced angiosperms. Here we analyzed telomere sequence in S. moellendorffii and found it to consist of TTTAGGG repeats, typical of most plants. Telomere tracts in S. moellendorffii range from 1 to 5.5 kb, closely resembling Arabidopsis thaliana. We identified several S. moellendorffii genes encoding sequence homologs of proteins involved in telomere maintenance in other organisms, including CST complex components and the telomere-binding proteins, POT1 and the TRFL family. Notable sequence similarities and differences were uncovered among the telomere-related genes in some of the plant lineages. Taken together, the data indicate that comparative analysis of the telomere complex in early diverging land plants such as S. moellendorffii and green algae will yield important insights into the evolution of telomeres and their protein constituents.
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Affiliation(s)
| | - Dorothy E. Shippen
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, TX, USA
- *Correspondence: Dorothy E. Shippen, Department of Biochemistry and Biophysics, Texas A&M University, 2128 TAMU, College Station, TX 77843-2128, USA. e-mail:
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13
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Amiard S, Depeiges A, Allain E, White CI, Gallego ME. Arabidopsis ATM and ATR kinases prevent propagation of genome damage caused by telomere dysfunction. THE PLANT CELL 2011; 23:4254-65. [PMID: 22158468 PMCID: PMC3269864 DOI: 10.1105/tpc.111.092387] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/06/2011] [Revised: 11/22/2011] [Accepted: 11/30/2011] [Indexed: 05/18/2023]
Abstract
The ends of linear eukaryotic chromosomes are hidden in nucleoprotein structures called telomeres, and loss of the telomere structure causes inappropriate repair, leading to severe karyotypic and genomic instability. Although it has been shown that DNA damaging agents activate a DNA damage response (DDR), little is known about the signaling of dysfunctional plant telomeres. We show that absence of telomerase in Arabidopsis thaliana elicits an ATAXIA-TELANGIECTASIA MUTATED (ATM) and ATM AND RAD3-RELATED (ATR)-dependent DDR at telomeres, principally through ATM. By contrast, telomere dysfunction induces an ATR-dependent response in telomeric Conserved telomere maintenance component1 (Ctc1)-Suppressor of cdc thirteen (Stn1)-Telomeric pathways in association with Stn1 (CST)-complex mutants. These results uncover a new role for the CST complex in repressing the ATR-dependent DDR pathway in plant cells and show that plant cells use two different DNA damage surveillance pathways to signal telomere dysfunction. The absence of either ATM or ATR in ctc1 and stn1 mutants significantly enhances developmental and genome instability while reducing stem cell death. These data thus give a clear illustration of the action of ATM/ATR-dependent programmed cell death in maintaining genomic integrity through elimination of genetically unstable cells.
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14
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Moriguchi R, Ohata K, Kanahama K, Takahashi H, Nishiyama M, Kanayama Y. Suppression of telomere-binding protein gene expression represses seed and fruit development in tomato. JOURNAL OF PLANT PHYSIOLOGY 2011; 168:1927-1933. [PMID: 21683470 DOI: 10.1016/j.jplph.2011.05.009] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/25/2011] [Revised: 05/17/2011] [Accepted: 05/23/2011] [Indexed: 05/30/2023]
Abstract
Tomato (Solanum lycopersicum L.) plants were transformed with an antisense construct of a cDNA encoding tomato telomere-binding protein (LeTBP1) to describe the role of a telomere-binding protein at the whole plant level. Fruit size decreased corresponding to the degree of suppression of LeTBP1 expression. This inhibition of fruit development was likely due to a decrease in the number of seeds in the LeTBP1 antisense plants. Pollen fertility and pollen germination rate decreased in accordance with the degree of suppression of LeTBP1 expression. Ovule viability was also reduced in the LeTBP1 antisense plants. Although plant height was somewhat reduced in the antisense plants compared to the control plants, the number and weight of leaves were unaffected by LeTBP1 suppression. The number and morphology of flowers were also normal in the antisense plants. These indicate that reduced fertility in the antisense plants is not an indirect effect of altered vegetative growth. LeTBP1 expression was sensitive to temperature stress in wild-type plants. We conclude that LeTBP1 plays a critical role in seed and fruit development rather than vegetative growth and flower formation.
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Affiliation(s)
- Ryo Moriguchi
- Graduate School of Agricultural Science, Tohoku University, Aoba-ku, Sendai 981-8555, Japan
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15
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Lee YW, Kim WT. Roles of NtGTBP1 in telomere stability. PLANT SIGNALING & BEHAVIOR 2011; 6:523-5. [PMID: 21474994 PMCID: PMC3142381 DOI: 10.4161/psb.6.4.14749] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/07/2011] [Accepted: 01/07/2011] [Indexed: 05/25/2023]
Abstract
Telomeres are protective nucleoprotein structures at the ends of linear eukaryotic chromosomes. In contrast to double-stranded-specific telomere-binding proteins, the cellular roles of single-stranded-specific telomeric proteins are not well understood in higher plants. Three highly conserved tobacco G-strand-specific telomere-binding protein paralogs (NtGTBP1, NtGTBP2, and NtGTBP3) were identified and characterized. All three NtGTBPs were able to bind specifically to the plant single-stranded telomeric repeat elements in vitro with similar affinities. Suppression of NtGTBP1 by means of the RNAi-mediated gene knock-down method resulted in developmental defects in transgenic tobacco plants accompanied by lengthened telomeres, extra-chromosomal telomeric circles, and abnormal anaphase bridges. These results suggest that the down-regulation of NtGTBP1 results in genome instability. NtGTBP1 prevented in vitro strand invasion, a prerequisite process for inter-chromosomal telomeric recombination. Therefore, tobacco NtGTBP1 is one of the essential factors for telomere stability. Because abnormal telomeric elongation and recombination due to the suppression of NtGTBP1 are reminiscent of the recombinational telomere lengthening mechanism that purportedly operates in telomerase negative cancer cells, it is of interest to investigate whether telomeric recombination is associated with cell death in animal systems.
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Affiliation(s)
- Yong Woo Lee
- Yonsei University, Department of Systems Biology, Seoul, South Korea
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16
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Higgins JD, Ferdous M, Osman K, Franklin FCH. The RecQ helicase AtRECQ4A is required to remove inter-chromosomal telomeric connections that arise during meiotic recombination in Arabidopsis. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2011; 65:492-502. [PMID: 21265901 DOI: 10.1111/j.1365-313x.2010.04438.x] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
RecQ helicases are a conserved group of proteins with a role in the maintenance of genome integrity. In Saccharomyces cerevisiae (budding yeast), meiotic recombination is increased in the absence of the RecQ helicase Sgs1. Here we investigated the potential meiotic role of the Sgs1 homologue AtRECQ4A and the closely related AtRECQ4B. Both proteins have been shown to function during recombination in somatic cells, but so far their meiotic role has not been investigated. Both AtRECQ4A and AtRECQ4B were expressed in reproductive tissues. Although immunolocalization studies showed that AtRECQ4A associates with recombination intermediates, we found no evidence that its loss or that of AtRECQ4B had a significant effect on meiotic cross-overs, suggesting functional redundancy with other RECQ family members. Nevertheless, pollen viability decreased in Atrecq4A, resulting in a reduction in fertility, although this was not the case in Atrecq4B. Cytological analysis revealed chromatin bridges between the telomeres of non-homologous chromosomes in Atrecq4A at metaphase I, in some instances accompanied by chromosome fragmentation at anaphase I. The bridges required telomeric repeats and were dependent on meiotic recombination. Immunolocalization confirmed the association of AtRECQ4A with the telomeres during prophase I, which we propose enables dissolution of recombination-dependent telomeric associations. Thus, this study has identified a hitherto unknown role for a member of the RECQ helicase family during meiosis that contributes to the maintenance of chromosome integrity. As telomere structure is generally conserved, it seems likely that these associations may arise during meiosis in other species, where they must also be removed.
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Affiliation(s)
- James D Higgins
- School of Biosciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK
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17
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Abstract
Telomerase is a ribonucleoprotein (RNP) reverse transcriptase whose essential RNA subunit (TER) functions as a template for telomere repeat synthesis. Here we report the identification of two divergent TER moieties in the flowering plant Arabidopsis thaliana. Although both TER1 and TER2 copurify with telomerase activity and serve as templates for telomerase in vitro, depletion of TER1, but not TER2, leads to decreased telomerase activity and progressive telomere shortening in vivo. Moreover, mutation of the templating domain in TER1 results in the incorporation of mutant telomere repeats on chromosome ends. Thus, TER1 provides the major template for telomerase in vivo. We also show that POT1a binds TER1 with a Kd of 2 × 10(-7) M and the two components assemble into an enzymatically active RNP in vivo. In contrast, TER1-POT1b and TER2-POT1a associations were not observed. In other organisms POT1 proteins bind telomeric DNA and provide chromosome end protection. We propose that duplication of TER and POT1 in Arabidopsis fueled the evolution of novel protein-nucleic acid interactions and the migration of POT1 from the telomere to the telomerase RNP.
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18
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Abstract
Telomeres are essential structures at the ends of eukaryotic chromosomes. Work on their structure and function began almost 70 years ago in plants and flies, continued through the Nobel Prize winning work on yeast and ciliates, and goes on today in many model and non-model organisms. The basic molecular mechanisms of telomeres are highly conserved throughout evolution, and our current understanding of how telomeres function is a conglomeration of insights gained from many different species. This review will compare the current knowledge of telomeres in plants with other organisms, with special focus on the functional length of telomeric DNA, the search for TRF homologs, the family of POT1 proteins, and the recent discovery of members of the CST complex.
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Affiliation(s)
- J Matthew Watson
- Gregor Mendel Institute of Molecular Plant Biology, Austrian Academy of Sciences, Vienna, Austria
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19
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Price CM, Boltz KA, Chaiken MF, Stewart JA, Beilstein MA, Shippen DE. Evolution of CST function in telomere maintenance. Cell Cycle 2010; 9:3157-65. [PMID: 20697207 DOI: 10.4161/cc.9.16.12547] [Citation(s) in RCA: 124] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Telomeres consist of an elaborate, higher-order DNA architecture, and a suite of proteins that provide protection for the chromosome terminus by blocking inappropriate recombination and nucleolytic attack. In addition, telomeres facilitate telomeric DNA replication by physical interactions with telomerase and the lagging strand replication machinery. The prevailing view has been that two distinct telomere capping complexes evolved, shelterin in vertebrates and a trimeric complex comprised of Cdc13, Stn1 and Ten1 (CST) in yeast. The recent discovery of a CST-like complex in plants and humans raises new questions about the composition of telomeres and their regulatory mechanisms in multicellular eukaryotes. In this review we discuss the evolving functions and interactions of CST components and their contributions to chromosome end protection and DNA replication.
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Affiliation(s)
- Carolyn M Price
- Department of Cancer and Cell Biology, University of Cincinnati, Cincinnati, OH, USA.
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20
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Lee YW, Kim WT. Tobacco GTBP1, a homolog of human heterogeneous nuclear ribonucleoprotein, protects telomeres from aberrant homologous recombination. THE PLANT CELL 2010; 22:2781-95. [PMID: 20798328 PMCID: PMC2947183 DOI: 10.1105/tpc.110.076778] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/19/2010] [Revised: 07/14/2010] [Accepted: 08/13/2010] [Indexed: 05/07/2023]
Abstract
Telomeres are nucleoprotein complexes essential for the integrity of eukaryotic chromosomes. Cellular roles of single-stranded telomeric DNA binding proteins have been extensively described in yeast and animals, but our knowledge about plant single-strand telomeric factors is rudimentary. Here, we investigated Nicotiana tabacum G-strand-specific single-stranded telomere binding proteins (GTBPs), homologs of a human heterogeneous nuclear ribonucleoprotein. GTBPs bound specifically to the plant single-stranded (TTTAGGG)(4) telomeric repeat element in vitro and were associated with telomeric sequences in tobacco BY-2 suspension cells. Transgenic plants (35S:RNAi-GTBP1), in which GTBP1 was suppressed, exhibited severe developmental anomalies. In addition, the chromosomes of 35S:RNAi-GTBP1 cells displayed elongated telomeres, frequent formation of extrachromosomal telomeric circles, and numerous abnormal anaphase bridges, indicating that GTBP1 knockdown tobacco plants experienced genome instability. GTBP1 inhibited strand invasion, an initial step in interchromosomal homologous recombination. We propose that GTBP1 plays a critical role in telomere structure and function by preventing aberrant interchromosomal telomeric homologous recombination in tobacco.
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Affiliation(s)
| | - Woo Taek Kim
- Department of Biology, College of Life Science and Biotechnology, Yonsei University, Seoul 120-749, Korea
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21
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Watson JM, Riha K. Comparative biology of telomeres: where plants stand. FEBS Lett 2010; 584:3752-9. [PMID: 20580356 PMCID: PMC3767043 DOI: 10.1016/j.febslet.2010.06.017] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2010] [Revised: 06/11/2010] [Accepted: 06/14/2010] [Indexed: 01/02/2023]
Abstract
Telomeres are essential structures at the ends of eukaryotic chromosomes. Work on their structure and function began almost 70 years ago in plants and flies, continued through the Nobel Prize winning work on yeast and ciliates, and goes on today in many model and non-model organisms. The basic molecular mechanisms of telomeres are highly conserved throughout evolution, and our current understanding of how telomeres function is a conglomeration of insights gained from many different species. This review will compare the current knowledge of telomeres in plants with other organisms, with special focus on the functional length of telomeric DNA, the search for TRF homologs, the family of POT1 proteins, and the recent discovery of members of the CST complex.
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Affiliation(s)
- J Matthew Watson
- Gregor Mendel Institute of Molecular Plant Biology, Austrian Academy of Sciences, Vienna, Austria
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22
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Shakirov EV, Perroud PF, Nelson AD, Cannell ME, Quatrano RS, Shippen DE. Protection of Telomeres 1 is required for telomere integrity in the moss Physcomitrella patens. THE PLANT CELL 2010; 22:1838-48. [PMID: 20515974 PMCID: PMC2910979 DOI: 10.1105/tpc.110.075846] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Abstract
In vertebrates, the single-stranded telomeric DNA binding protein Protection of Telomeres 1 (POT1) shields chromosome ends and prevents them from eliciting a DNA damage response. By contrast, Arabidopsis thaliana encodes two divergent full-length POT1 paralogs that do not exhibit telomeric DNA binding in vitro and have evolved to mediate telomerase regulation instead of chromosome end protection. To further investigate the role of POT1 in plants, we established the moss Physcomitrella patens as a new model for telomere biology and a counterpoint to Arabidopsis. The sequence and architecture of the telomere tract is similar in P. patens and Arabidopsis, but P. patens harbors only a single-copy POT1 gene. Unlike At POT1 proteins, Pp POT1 efficiently bound single-stranded telomeric DNA in vitro. Deletion of the P. patens POT1 gene resulted in the rapid onset of severe developmental defects and sterility. Although telomerase activity levels were unperturbed, telomeres were substantially shortened, harbored extended G-overhangs, and engaged in end-to-end fusions. We conclude that the telomere capping function of POT1 is conserved in early diverging land plants but is subsequently lost in Arabidopsis.
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Affiliation(s)
- Eugene V. Shakirov
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, Texas 77843-2128
| | | | - Andrew D. Nelson
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, Texas 77843-2128
| | - Maren E. Cannell
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, Texas 77843-2128
| | - Ralph S. Quatrano
- Department of Biology, Washington University, St. Louis, Missouri 63130
| | - Dorothy E. Shippen
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, Texas 77843-2128
- Address correspondence to
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23
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Abstract
Proteins that specifically bind the single-stranded overhang at the ends of telomeres have been identified in a wide range of eukaryotes and play pivotal roles in chromosome end protection and telomere length regulation. Here we summarize recent findings regarding the functions of POT1 proteins in vertebrates and discuss the functional evolution of POT1 proteins following gene duplication in protozoa, plants, nematodes and mice.
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Affiliation(s)
- Peter Baumann
- Howard Hughes Medical Institute, Stowers Institute for Medical Research, Kansas City, MO 64110, USA.
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24
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Shakirov EV, Song X, Joseph JA, Shippen DE. POT1 proteins in green algae and land plants: DNA-binding properties and evidence of co-evolution with telomeric DNA. Nucleic Acids Res 2010; 37:7455-67. [PMID: 19783822 PMCID: PMC2794166 DOI: 10.1093/nar/gkp785] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Telomeric DNA terminates with a single-stranded 3′ G-overhang that in vertebrates and fission yeast is bound by POT1 (Protection Of Telomeres). However, no in vitro telomeric DNA binding is associated with Arabidopsis POT1 paralogs. To further investigate POT1–DNA interaction in plants, we cloned POT1 genes from 11 plant species representing major branches of plant kingdom. Telomeric DNA binding was associated with POT1 proteins from the green alga Ostreococcus lucimarinus and two flowering plants, maize and Asparagus. Site-directed mutagenesis revealed that several residues critical for telomeric DNA recognition in vertebrates are functionally conserved in plant POT1 proteins. However, the plant proteins varied in their minimal DNA-binding sites and nucleotide recognition properties. Green alga POT1 exhibited a strong preference for the canonical plant telomere repeat sequence TTTAGGG with no detectable binding to hexanucleotide telomere repeat TTAGGG found in vertebrates and some plants, including Asparagus. In contrast, POT1 proteins from maize and Asparagus bound TTAGGG repeats with only slightly reduced affinity relative to the TTTAGGG sequence. We conclude that the nucleic acid binding site in plant POT1 proteins is evolving rapidly, and that the recent acquisition of TTAGGG telomere repeats in Asparagus appears to have co-evolved with changes in POT1 DNA sequence recognition.
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Affiliation(s)
- Eugene V Shakirov
- Department of Biochemistry and Biophysics, Texas A&M University, 2128 TAMU, College Station, TX 77843-2128, USA
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25
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HipHop interacts with HOAP and HP1 to protect Drosophila telomeres in a sequence-independent manner. EMBO J 2010; 29:819-29. [PMID: 20057353 DOI: 10.1038/emboj.2009.394] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2009] [Accepted: 12/08/2009] [Indexed: 12/30/2022] Open
Abstract
Telomeres prevent chromosome ends from being repaired as double-strand breaks (DSBs). Telomere identity in Drosophila is determined epigenetically with no sequence either necessary or sufficient. To better understand this sequence-independent capping mechanism, we isolated proteins that interact with the HP1/ORC-associated protein (HOAP) capping protein, and identified HipHop as a subunit of the complex. Loss of one protein destabilizes the other and renders telomeres susceptible to fusion. Both HipHop and HOAP are enriched at telomeres, where they also interact with the conserved HP1 protein. We developed a model telomere lacking repetitive sequences to study the distribution of HipHop, HOAP and HP1 using chromatin immunoprecipitation (ChIP). We discovered that they occupy a broad region >10 kb from the chromosome end and their binding is independent of the underlying DNA sequence. HipHop and HOAP are both rapidly evolving proteins yet their telomeric deposition is under the control of the conserved ATM and Mre11-Rad50-Nbs (MRN) proteins that modulate DNA structures at telomeres and at DSBs. Our characterization of HipHop and HOAP reveals functional analogies between the Drosophila proteins and subunits of the yeast and mammalian capping complexes, implicating conservation in epigenetic capping mechanisms.
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26
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Linger BR, Price CM. Conservation of telomere protein complexes: shuffling through evolution. Crit Rev Biochem Mol Biol 2009; 44:434-46. [PMID: 19839711 DOI: 10.3109/10409230903307329] [Citation(s) in RCA: 74] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
The rapid evolution of telomere proteins has hindered identification of orthologs from diverse species and created the impression that certain groups of eukaryotes have largely non-overlapping sets of telomere proteins. However, the recent identification of additional telomere proteins from various model organisms has dispelled this notion by expanding our understanding of the composition, architecture and range of telomere protein complexes present in individual species. It is now apparent that versions of the budding yeast CST complex and mammalian shelterin are present in multiple phyla. While the precise subunit composition and architecture of these complexes vary between species, the general function is often conserved. Despite the overall conservation of telomere protein complexes, there is still considerable species-specific variation, with some organisms having lost a particular subunit or even an entire complex. In some cases, complex components appear to have migrated between the telomere and the telomerase RNP. Finally, gene duplication has created telomere protein paralogs with novel functions. While one paralog may be part of a conserved telomere protein complex and have the expected function, the other paralog may serve in a completely different aspect of telomere biology.
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Affiliation(s)
- Benjamin R Linger
- Department of Cancer and Cell Biology, University of Cincinnati, Cincinnati, OH 45267-0521, USA
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