Telomere repeat binding proteins (TRBs) belong to a family of proteins possessing a Myb-like domain which binds to telomeric repeats. Three members of this family (TRB1, TRB2, TRB3) from Arabidopsis thaliana have already been described as associated with terminal telomeric repeats (telomeres) or short interstitial telomeric repeats in gene promoters (telo-boxes). They are also known to interact with several protein complexes: telomerase, Polycomb repressive complex 2 (PRC2) E(z) subunits and the PEAT complex (PWOs-EPCRs-ARIDs-TRBs). Here we characterize two novel members of the TRB family (TRB4 and TRB5). Our wide phylogenetic analyses have shown that TRB proteins evolved in the plant kingdom after the transition to a terrestrial habitat in Streptophyta, and consequently TRBs diversified in seed plants. TRB4-5 share common TRB motifs while differing in several others and seem to have an earlier phylogenetic origin than TRB1-3. Their common Myb-like domains bind long arrays of telomeric repeats in vitro, and we have determined the minimal recognition motif of all TRBs as one telo-box. Our data indicate that despite the distinct localization patterns of TRB1-3 and TRB4-5 in situ, all members of TRB family mutually interact and also bind to telomerase/PRC2/PEAT complexes. Additionally, we have detected novel interactions between TRB4-5 and EMF2 and VRN2, which are Su(z)12 subunits of PRC2.

• Klíčová slova
• PEAT, PRC2, TERT, TRB, Telomere repeat binding, Telomeric,
• MeSH
• Arabidopsis * genetika   metabolismus   MeSH
• fylogeneze MeSH
• proteiny huseníčku * genetika   metabolismus   MeSH
• proteiny vázající telomery genetika   metabolismus   MeSH
• půda MeSH
• telomerasa * genetika   metabolismus   MeSH
• telomery genetika   metabolismus   MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• proteiny huseníčku * MeSH
• proteiny vázající telomery MeSH
• půda MeSH
• telomerasa * MeSH

Telomeres are essential structures formed from satellite DNA repeats at the ends of chromosomes in most eukaryotes. Satellite DNA repeat sequences are useful markers for karyotyping, but have a more enigmatic role in the eukaryotic cell. Much work has been done to investigate the structure and arrangement of repetitive DNA elements in classical models with implications for species evolution. Still more is needed until there is a complete picture of the biological function of DNA satellite sequences, particularly when considering non-model organisms. Celebrating Gregor Mendel's anniversary by going to the roots, this review is designed to inspire and aid new research into telomeres and satellites with a particular focus on non-model organisms and accessible experimental and in silico methods that do not require specialized equipment or expensive materials. We describe how to identify telomere (and satellite) repeats giving many examples of published (and some unpublished) data from these techniques to illustrate the principles behind the experiments. We also present advice on how to perform and analyse such experiments, including details of common pitfalls. Our examples are a selection of recent developments and underexplored areas of research from the past. As a nod to Mendel's early work, we use many examples from plants and insects, especially as much recent work has expanded beyond the human and yeast models traditional in telomere research. We give a general introduction to the accepted knowledge of telomere and satellite systems and include references to specialized reviews for the interested reader.

• Klíčová slova
• FISH, NGS, TRAP, eukaryotic tree of life, interstitial telomere sequences, retroelements, satellite, subtelomere structure, telomerase RNA, telomere evolution,
• MeSH
• DNA MeSH
• lidé MeSH
• repetitivní sekvence nukleových kyselin MeSH
• satelitní DNA * MeSH
• sekvence nukleotidů MeSH
• telomery * genetika   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• přehledy MeSH
• Názvy látek
• DNA MeSH
• satelitní DNA * MeSH

Parallel research on multiple model organisms shows that while some principles of telomere biology are conserved among all eukaryotic kingdoms, we also find some deviations that reflect different evolutionary paths and life strategies, which may have diversified after the establishment of telomerase as a primary mechanism for telomere maintenance. Much more than animals, plants have to cope with environmental stressors, including genotoxic factors, due to their sessile lifestyle. This is, in principle, made possible by an increased capacity and efficiency of the molecular systems ensuring maintenance of genome stability, as well as a higher tolerance to genome instability. Furthermore, plant ontogenesis differs from that of animals in which tissue differentiation and telomerase silencing occur during early embryonic development, and the "telomere clock" in somatic cells may act as a preventive measure against carcinogenesis. This does not happen in plants, where growth and ontogenesis occur through the serial division of apical meristems consisting of a small group of stem cells that generate a linear series of cells, which differentiate into an array of cell types that make a shoot and root. Flowers, as generative plant organs, initiate from the shoot apical meristem in mature plants which is incompatible with the human-like developmental telomere shortening. In this review, we discuss differences between human and plant telomere biology and the implications for aging, genome stability, and cell and organism survival. In particular, we provide a comprehensive comparative overview of telomere proteins acting in humans and in Arabidopsis thaliana model plant, and discuss distinct epigenetic features of telomeric chromatin in these species.

• Klíčová slova
• Arabidopsis, aging, chromatin, epigenetics, human, review, telomerase, telomere,
• MeSH
• chromatin metabolismus   MeSH
• epigeneze genetická MeSH
• lidé MeSH
• rostliny metabolismus   MeSH
• stárnutí buněk genetika   MeSH
• telomerasa metabolismus   MeSH
• telomery metabolismus   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• přehledy MeSH
• Názvy látek
• chromatin MeSH
• telomerasa MeSH

Arabidopsis and human ARM protein interact with telomerase. Deregulated mRNA levels of DNA repair and ribosomal protein genes in an Arabidopsis arm mutant suggest non-telomeric ARM function. The human homolog ARMC6 interacts with hTRF2. Telomerase maintains telomeres and has proposed non-telomeric functions. We previously identified interaction of the C-terminal domain of Arabidopsis telomerase reverse transcriptase (AtTERT) with an armadillo/β-catenin-like repeat (ARM) containing protein. Here we explore protein-protein interactions of the ARM protein, AtTERT domains, POT1a, TRF-like family and SMH family proteins, and the chromatin remodeling protein CHR19 using bimolecular fluorescence complementation (BiFC), yeast two-hybrid (Y2H) analysis, and co-immunoprecipitation. The ARM protein interacts with both the N- and C-terminal domains of AtTERT in different cellular compartments. ARM interacts with CHR19 and TRF-like I family proteins that also bind AtTERT directly or through interaction with POT1a. The putative human ARM homolog co-precipitates telomerase activity and interacts with hTRF2 protein in vitro. Analysis of Arabidopsis arm mutants shows no obvious changes in telomere length or telomerase activity, suggesting that ARM is not essential for telomere maintenance. The observed interactions with telomerase and Myb-like domain proteins (TRF-like family I) may therefore reflect possible non-telomeric functions. Transcript levels of several DNA repair and ribosomal genes are affected in arm mutants, and ARM, likely in association with other proteins, suppressed expression of XRCC3 and RPSAA promoter constructs in luciferase reporter assays. In conclusion, ARM can participate in non-telomeric functions of telomerase, and can also perform its own telomerase-independent functions.

• Klíčová slova
• ARMC6, Armadillo/β-catenin-like repeat, AtTERT, Homologous recombination, Protein–protein interaction, Telomerase activity,
• MeSH
• Arabidopsis enzymologie   genetika   MeSH
• holoenzymy MeSH
• lidé MeSH
• proteiny huseníčku genetika   metabolismus   MeSH
• proteiny s doménou armadillo genetika   metabolismus   MeSH
• reportérové geny MeSH
• techniky dvojhybridového systému MeSH
• telomerasa genetika   metabolismus   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• ARMC6 protein, human MeSH Prohlížeč
• holoenzymy MeSH
• proteiny huseníčku MeSH
• proteiny s doménou armadillo MeSH
• telomerasa MeSH

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.

• Klíčová slova
• plant, shelterin, telomerase, telomere, telomeric proteins, telomeric repeat binding (TRB),
• Publikační typ
• časopisecké články MeSH
• přehledy MeSH