scholarly journals The C Terminus of the Major Yeast Telomere Binding Protein Rap1p Enhances Telomere Formation

1998 ◽  
Vol 18 (3) ◽  
pp. 1284-1295 ◽  
Author(s):  
Alo Ray ◽  
Kurt W. Runge
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Reverse Transcriptase ◽  
Binding Site ◽  
Binding Protein ◽  
Telomerase Activity ◽  
Telomerase Rna ◽  
Constant Length ◽  
C Terminus ◽  
Telomere Binding Protein ◽  
Yeast Telomere

ABSTRACT The telomeres of most organisms consist of short repeated sequences that can be elongated by telomerase, a reverse transcriptase complex that contains its own RNA template for the synthesis of telomere repeats. In Saccharomyces cerevisiae, the RAP1gene encodes the major telomere binding protein Rap1p. Here we use a quantitative telomere formation assay to demonstrate that Rap1p C termini can enhance telomere formation more than 30-fold when they are located at internal sites. This stimulation is distinct from protection from degradation. Enhancement of formation required the gene for telomerase RNA but not Sir1p, Sir2p, Sir3p, Sir4p, Tel1p, or the Rif1p binding site in the Rap1p C terminus. Our data suggest that Rap1p C termini enhance telomere formation by attracting or increasing the activity of telomerase near telomeres. Earlier work suggests that Rap1p molecules at the chromosome terminus inhibit the elongation of long telomeres by blocking the access of telomerase. Our results suggest a model where a balance between internal Rap1p increasing telomerase activity and Rap1p at the termini of long telomeres controlling telomerase access maintains telomeres at a constant length.

scholarly journals Telomerase Activity Reconstitutedin Vitrowith Purified Human Telomerase Reverse Transcriptase and Human Telomerase RNA Component

2000 ◽  
Vol 275 (29) ◽  
pp. 22568-22573 ◽  
Author(s):  
Kenkichi Masutomi ◽  
Shuichi Kaneko ◽  
Naoyuki Hayashi ◽  
Tatsuya Yamashita ◽  
Yukihiro Shirota ◽  
...  
Keyword(s):  
Reverse Transcriptase ◽  
Telomerase Activity ◽  
Telomerase Reverse Transcriptase ◽  
Telomerase Rna ◽  
Human Telomerase Reverse Transcriptase ◽  
Human Telomerase

scholarly journals Telomerase biogenesis requires a novel Mex67 function and a cytoplasmic association with the Sm7 complex

eLife ◽  
2020 ◽  
Vol 9 ◽  
Author(s):  
Yulia Vasianovich ◽  
Emmanuel Bajon ◽  
Raymund J Wellinger
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Life Cycle ◽  
Reverse Transcriptase ◽  
Nuclear Export ◽  
Complex Life Cycle ◽  
Telomerase Reverse Transcriptase ◽  
Telomerase Rna ◽  
The Core ◽  
Nuclear Stability

The templating RNA is the core of the telomerase reverse transcriptase. In Saccharomyces cerevisiae, the complex life cycle and maturation of telomerase includes a cytoplasmic stage. However, timing and reason for this cytoplasmic passage are poorly understood. Here, we use inducible RNA tagging experiments to show that immediately after transcription, newly synthesized telomerase RNAs undergo one round of nucleo-cytoplasmic shuttling. Their export depends entirely on Crm1/Xpo1, whereas re-import is mediated by Kap122 plus redundant, kinetically less efficient import pathways. Strikingly, Mex67 is essential to stabilize newly transcribed RNA before Xpo1-mediated nuclear export. The results further show that the Sm7 complex associates with and stabilizes the telomerase RNA in the cytoplasm and promotes its nuclear re-import. Remarkably, after this cytoplasmic passage, the nuclear stability of telomerase RNA no longer depends on Mex67. These results underscore the utility of inducible RNA tagging and challenge current models of telomerase maturation.

scholarly journals Progesterone Receptor Membrane Component-1 (PGRMC1) Is the Mediator of Progesterone’s Antiapoptotic Action in Spontaneously Immortalized Granulosa Cells As Revealed by PGRMC1 Small Interfering Ribonucleic Acid Treatment and Functional Analysis of PGRMC1 Mutations

Endocrinology ◽  
2007 ◽  
Vol 149 (2) ◽  
pp. 534-543 ◽  
Author(s):  
John J. Peluso ◽  
Jonathan Romak ◽  
Xiufang Liu
Keyword(s):  
Binding Site ◽  
Rna Binding ◽  
Transmembrane Domain ◽  
Binding Protein ◽  
Plasminogen Activator Inhibitor ◽  
Membrane Receptor ◽  
Membrane Component ◽  
Plasminogen Activator Inhibitor 1 ◽  
Receptor Membrane ◽  
C Terminus

Progesterone (P4) receptor membrane component-1 (PGRMC1) and its binding partner, plasminogen activator inhibitor 1 RNA binding protein (PAIRBP1) are thought to form a complex that functions as membrane receptor for P4. The present investigations confirm PGRMC1’s role in this membrane receptor complex by demonstrating that depleting PGMRC1 with PGRMC1 small interfering RNA results in a 60% decline in [3H]P4 binding and the loss of P4’s antiapoptotic action. Studies conducted on partially purified GFP-PGRMC1 fusion protein indicate that [3H]P4 specifically binds to PGRMC1 at a single site with an apparent Kd of about 35 nm. In addition, experiments using various deletion mutations reveal that the entire PGRMC1 molecule is required for maximal [3H]P4 binding and P4 responsiveness. Analysis of the binding data also suggests that the P4 binding site is within a segment of PGRMC1 that is composed of the transmembrane domain and the initial segment of the C terminus. Interestingly, PAIRBP1 appears to bind to the C terminus between amino acids 70–130, which is distal to the putative P4 binding site. Taken together, these data provide compelling evidence that PGRMC1 is the P4 binding protein that mediates P4’s antiapoptotic action. Moreover, the deletion mutation studies indicate that each domain of PGRMC1 plays an essential role in modulating PGRMC1’s capacity to both bind and respond to P4. Additional studies are required to more precisely delineate the role of each PGRMC1 domain in transducing P4’s antiapoptotic action.

Telomerase Reverse Transcriptase (hTERT) mRNA and Telomerase RNA (hTR) as Targets for Downregulation of Telomerase Activity

2004 ◽  
Vol 14 (4) ◽  
pp. 263-273 ◽  
Author(s):  
Shobhana Natarajan ◽  
Zhi Chen ◽  
Edward V. Wancewicz ◽  
Brett P. Monia ◽  
David R. Corey
Keyword(s):  
Reverse Transcriptase ◽  
Telomerase Activity ◽  
Telomerase Reverse Transcriptase ◽  
Telomerase Rna ◽  
Htert Mrna

scholarly journals Fission yeast telomere-binding protein Taz1 is a functional but not a structural counterpart of human TRF1 and TRF2

Cell Research ◽  
2015 ◽  
Vol 25 (7) ◽  
pp. 881-884 ◽  
Author(s):  
Wei Deng ◽  
Jian Wu ◽  
Feng Wang ◽  
Junko Kanoh ◽  
Pierre-Marie Dehe ◽  
...  
Keyword(s):  
Fission Yeast ◽  
Binding Protein ◽  
Telomere Binding Protein ◽  
Yeast Telomere

scholarly journals Structural conservation in the template/pseudoknot domain of vertebrate telomerase RNA from teleost fish to human

2016 ◽  
Vol 113 (35) ◽  
pp. E5125-E5134 ◽  
Author(s):  
Yaqiang Wang ◽  
Joseph D. Yesselman ◽  
Qi Zhang ◽  
Mijeong Kang ◽  
Juli Feigon
Keyword(s):  
Reverse Transcriptase ◽  
Teleost Fish ◽  
Telomerase Activity ◽  
Full Length ◽  
Telomerase Rna ◽  
Dna Repeats ◽  
Base Pairs ◽  
Tertiary Interactions ◽  
Linear Chromosomes

Telomerase is an RNA–protein complex that includes a unique reverse transcriptase that catalyzes the addition of single-stranded telomere DNA repeats onto the 3′ ends of linear chromosomes using an integral telomerase RNA (TR) template. Vertebrate TR contains the template/pseudoknot (t/PK) and CR4/5 domains required for telomerase activity in vitro. All vertebrate pseudoknots include two subdomains: P2ab (helices P2a and P2b with a 5/6-nt internal loop) and the minimal pseudoknot (P2b–P3 and associated loops). A helical extension of P2a, P2a.1, is specific to mammalian TR. Using NMR, we investigated the structures of the full-length TR pseudoknot and isolated subdomains in Oryzias latipes (Japanese medaka fish), which has the smallest vertebrate TR identified to date. We determined the solution NMR structure and studied the dynamics of medaka P2ab, and identified all base pairs and tertiary interactions in the minimal pseudoknot. Despite differences in length and sequence, the structure of medaka P2ab is more similar to human P2ab than predicted, and the medaka minimal pseudoknot has the same tertiary interactions as the human pseudoknot. Significantly, although P2a.1 is not predicted to form in teleost fish, we find that it forms in the full-length pseudoknot via an unexpected hairpin. Model structures of the subdomains are combined to generate a model of t/PK. These results provide evidence that the architecture for the vertebrate t/PK is conserved from teleost fish to human. The organization of the t/PK on telomerase reverse transcriptase for medaka and human is modeled based on the cryoEM structure of Tetrahymena telomerase, providing insight into function.

scholarly journals Tetrahymena Telomerase Protein p65 Induces Conformational Changes throughout Telomerase RNA (TER) and Rescues Telomerase Reverse Transcriptase and TER Assembly Mutants

2010 ◽  
Vol 30 (20) ◽  
pp. 4965-4976 ◽  
Author(s):  
Andrea J. Berman ◽  
Anne R. Gooding ◽  
Thomas R. Cech
Keyword(s):  
Reverse Transcriptase ◽  
Single Molecule ◽  
Conformational Changes ◽  
Mutational Analysis ◽  
Telomerase Activity ◽  
Telomerase Reverse Transcriptase ◽  
Telomerase Rna ◽  
Hierarchical Assembly ◽  
Family Protein ◽  
Catalytically Active

ABSTRACT The biogenesis of the Tetrahymena telomerase ribonucleoprotein particle (RNP) is enhanced by p65, a La family protein. Single-molecule and biochemical studies have uncovered a hierarchical assembly of the RNP, wherein the binding of p65 to stems I and IV of telomerase RNA (TER) causes a conformational change that facilitates the subsequent binding of telomerase reverse transcriptase (TERT) to TER. We used purified p65 and variants of TERT and TER to investigate the conformational rearrangements that occur during RNP assembly. Nuclease protection assays and mutational analysis revealed that p65 interacts with and stimulates conformational changes in regions of TER beyond stem IV. Several TER mutants exhibited telomerase activity only in the presence of p65, revealing the importance of p65 in promoting the correct RNP assembly pathway. In addition, p65 rescued TERT assembly mutants but not TERT activity mutants. Taken together, these results suggest that p65 stimulates telomerase assembly and activity in two ways. First, by sequestering stems I and IV, p65 limits the ensemble of structural conformations of TER, thereby presenting TERT with the active conformation of TER. Second, p65 acts as a molecular buttress within the assembled RNP, mutually stabilizing TER and TERT in catalytically active conformations.

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