A miniature yeast telomerase RNA functions in vivo and reconstitutes activity in vitro

2005 ◽  
Vol 12 (12) ◽  
pp. 1072-1077 ◽  
Author(s):  
David C Zappulla ◽  
Karen Goodrich ◽  
Thomas R Cech
Keyword(s):  
Telomerase Rna ◽  
Yeast Telomerase

scholarly journals A 4-base pair core-enclosing helix in telomerase RNA is essential and binds to the TERT catalytic protein subunit

2020 ◽  
Author(s):  
Melissa A. Mefford ◽  
Evan P. Hass ◽  
David C. Zappulla
Keyword(s):  
Telomerase Activity ◽  
Genome Replication ◽  
Telomerase Rna ◽  
Protein Subunit ◽  
Base Pairs ◽  
Binding Interaction ◽  
Catalytic Core ◽  
Yeast Telomerase

ABSTRACTThe telomerase RNP counters the chromosome end-replication problem, completing genome replication to prevent cellular senescence in yeast, humans, and most other eukaryotes. The telomerase RNP core enzyme is composed of a dedicated RNA subunit and a reverse transcriptase (TERT). Although the majority of the 1157-nt Saccharomyces cerevisiae telomerase RNA, TLC1, is rapidly evolving, the central catalytic core is largely conserved, containing the template, template-boundary helix, pseudoknot, and core-enclosing helix (CEH). Here, we show that 4-base pairs of core-enclosing helix is required for telomerase to be active in vitro and to maintain yeast telomeres in vivo, whereas ΔCEH, 1-bp, and 2-bp alleles do not support telomerase function. Using the CRISPR/dCas9-based “CARRY two-hybrid” assay to assess binding of our CEH mutant RNAs to TERT, we find that the 4-bp CEH RNA binds to TERT, but the shorter-CEH constructs do not, consistent with the telomerase activity and in vivo complementation results. Thus, the CEH is essential in yeast telomerase RNA because it is needed to bind TERT to form the core RNP enzyme. Although the 8 nucleotides that form this 4-bp stem at the base of the CEH are nearly invariant among Saccharomyces species, our results with sequence-randomized and truncated-CEH helices strongly suggest that this binding interaction with TERT is dictated more by secondary than primary structure. In summary, we have mapped an essential binding site in telomerase RNA for TERT that is crucial to form the catalytic core of this biomedically important RNP enzyme.

scholarly journals Stiffened yeast telomerase RNA supports RNP function in vitro and in vivo

RNA ◽  
2012 ◽  
Vol 18 (9) ◽  
pp. 1666-1678 ◽  
Author(s):  
K. J. Lebo ◽  
D. C. Zappulla
Keyword(s):  
Telomerase Rna ◽  
Yeast Telomerase

scholarly journals The conserved structure of plant telomerase RNA provides the missing link for an evolutionary pathway from ciliates to humans

2019 ◽  
Vol 116 (49) ◽  
pp. 24542-24550 ◽  
Author(s):  
Jiarui Song ◽  
Dhenugen Logeswaran ◽  
Claudia Castillo-González ◽  
Yang Li ◽  
Sreyashree Bose ◽  
...  
Keyword(s):  
Telomerase Activity ◽  
Telomere Maintenance ◽  
Telomerase Rna ◽  
Telomeric Dna ◽  
Structural Element ◽  
Stem Loop ◽  
Evolutionary Pathway ◽  
Pol Iii

Telomerase is essential for maintaining telomere integrity. Although telomerase function is widely conserved, the integral telomerase RNA (TR) that provides a template for telomeric DNA synthesis has diverged dramatically. Nevertheless, TR molecules retain 2 highly conserved structural domains critical for catalysis: a template-proximal pseudoknot (PK) structure and a downstream stem-loop structure. Here we introduce the authentic TR from the plant Arabidopsis thaliana, called AtTR, identified through next-generation sequencing of RNAs copurifying with Arabidopsis TERT. This RNA is distinct from the RNA previously described as the templating telomerase RNA, AtTER1. AtTR is a 268-nt Pol III transcript necessary for telomere maintenance in vivo and sufficient with TERT to reconstitute telomerase activity in vitro. Bioinformatics analysis identified 85 AtTR orthologs from 3 major clades of plants: angiosperms, gymnosperms, and lycophytes. Through phylogenetic comparisons, a secondary structure model conserved among plant TRs was inferred and verified using in vitro and in vivo chemical probing. The conserved plant TR structure contains a template-PK core domain enclosed by a P1 stem and a 3′ long-stem P4/5/6, both of which resemble a corresponding structural element in ciliate and vertebrate TRs. However, the plant TR contains additional stems and linkers within the template-PK core, allowing for expansion of PK structure from the simple PK in the smaller ciliate TR during evolution. Thus, the plant TR provides an evolutionary bridge that unites the disparate structures of previously characterized TRs from ciliates and vertebrates.

Mouse prostate tumor inhibition via disruption of murine telomerase: In vivo and in vitro data for a new preclinical cancer model

2009 ◽  
Vol 27 (15_suppl) ◽  
pp. e14631-e14631
Author(s):  
T. Xu ◽  
Y. Xu ◽  
R. Lao ◽  
K. He ◽  
L. Xue ◽  
...  
Keyword(s):  
Prostate Cancer ◽  
Dna Damage ◽  
Cancer Cells ◽  
Cancer Cell Line ◽  
Telomerase Activity ◽  
Telomerase Rna ◽  
Prostate Cancer Cells ◽  
Mouse Prostate

e14631 Background: Telomerase-interference (TI), a novel therapeutic strategy, exploits the high telomerase activity in prostate cancer by introducing a mutated telomerase RNA (MT-Ter) that encodes toxic telomeres. Until now, TI has been tested by targeting human telomerase in tumor cells xenografted into immuno-deficient mice, an inadequate model for predicting efficacy and toxicity. We designed and validated 2 new TI gene constructs that specifically target murine telomerase RNA (mTER), enabling the study of TI in preclinical mouse models that are immuno-competent and that develop endogenous prostate tumors. Methods: We designed 2 constructs and cloned them into a lentiviral delivery system: MT-mTER and siRNA against wild type mTer (α-mTer-siRNA). Using a mouse prostate cancer cell line, E4, we tested the 2 constructs for expression (RT-PCR), telomerase activity (TRAP), and biologic activity (53bp1 DNA damage staining, MTS growth assay, TUNEL and caspase apoptosis assays), as well as in vivo efficacy (NOD-SCID allografts). Results: We confirmed MT-mTER expression (∼50-fold) and showed that α-mTer-siRNA specifically depleted WT-mTER (80% reduction) but not MT-mTER when the 2 constructs are co-expressed; thus, the 2 constructs in combination effectively substituted MT-mTer for WT-mTer in the mouse prostate cancer cells. MT-mTER caused mutant telomeric repeats (TTTGGG instead of TTAGGG) to be added to the ends of telomeres, resulting in rapid telomeric uncapping marked by 53bp1 DNA damage foci (an average 7.5 foci/cell vs. 1.4 foci/cell in vector control). This, in turn, led to rapid and significant apoptosis (>90% TUNEL and caspase +) and growth inhibition in vitro (90% reduction by MTS) and in vivo (75% reduction in tumor allograft size). Conclusions: We successfully designed and validated MT-mTer and α-mTer-siRNA, 2 novel gene constructs that specifically target and co-opt murine telomerase activity within mouse prostate cancer cells. These constructs offer a significant advantage, as they can be used to investigate TI in immuno-competent mice that develop prostate cancer, thereby modeling actual human disease and testing TI-based therapies in a much more informative and authentic manner. No significant financial relationships to disclose.

scholarly journals Polymerization Defects within Human Telomerase Are Distinct from Telomerase RNA and TEP1 Binding

2000 ◽  
Vol 11 (10) ◽  
pp. 3329-3340 ◽  
Author(s):  
Tara L. Beattie ◽  
Wen Zhou ◽  
Murray O. Robinson ◽  
Lea Harrington
Keyword(s):  
Telomerase Activity ◽  
Amino Terminus ◽  
Telomerase Rna ◽  
Carboxy Terminus ◽  
Active Core ◽  
Human Telomerase ◽  
Precise Role

The minimal, active core of human telomerase is postulated to contain two components, the telomerase RNA hTER and the telomerase reverse transcriptase hTERT. The reconstitution of human telomerase activity in vitro has facilitated the identification of sequences within the telomerase RNA and the RT motifs of hTERT that are essential for telomerase activity. However, the precise role of residues outside the RT domain of hTERT is unknown. Here we have delineated several regions within hTERT that are important for telomerase catalysis, primer use, and interaction with the telomerase RNA and the telomerase-associated protein TEP1. In particular, certain deletions of the amino and carboxy terminus of hTERT that retained an interaction with telomerase RNA and TEP1 were nonetheless completely inactive in vitro and in vivo. Furthermore, hTERT truncations lacking the amino terminus that were competent to bind the telomerase RNA were severely compromised for the ability to elongate telomeric and nontelomeric primers. These results suggest that the interaction of telomerase RNA with hTERT can be functionally uncoupled from polymerization, and that there are regions outside the RT domain of hTERT that are critical for telomerase activity and primer use. These results establish that the human telomerase RT possesses unique polymerization determinants that distinguish it from other RTs.

scholarly journals The yeast telomerase RNA, TLC1, participates in two distinct modes of TLC1-TLC1 association processes in vivo

2015 ◽  
Author(s):  
Tet Matsuguchi ◽  
Elizabeth Blackburn
Keyword(s):  
Nuclear Periphery ◽  
Repeat Sequence ◽  
Telomeric Repeat ◽  
G1 Phase ◽  
Telomerase Rna ◽  
Reverse Transcriptase Domain ◽  
Core Enzyme ◽  
Yeast Telomerase ◽  
Enzymatic Activation

Telomerase core enzyme minimally consists of the telomerase reverse transcriptase domain-containing protein (Est2 in budding yeast S. cerevisiae) and telomerase RNA, which contains the template specifying the telomeric repeat sequence synthesized. Here we report that in vivo, a fraction of S. cerevisiae telomerase RNA (TLC1) molecules form complexes containing at least two molecules of TLC1, via two separable modes: one requiring a sequence in the 3’ region of the immature TLC1 precursor and the other requiring Ku and Sir4. Such physical TLC1-TLC1 association peaked in G1 phase and did not require telomere silencing, telomere tethering to the nuclear periphery, telomerase holoenzyme assembly, or detectable Est2-Est2 protein association. These data indicate that TLC1-TLC1 associations reflect processes occurring during telomerase biogenesis; we propose that TLC1-TLC1 associations and subsequent reorganization may be regulatory steps in telomerase enzymatic activation.

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