The 5′ Arm of <i>Kluyveromyces lactis</i> Telomerase RNA Is Critical for Telomerase Function

Kabaha, Majdi M.; Zhitomirsky, Benny; Schwartz, Irit; Tzfati, Yehuda

doi:10.1128/mcb.01683-07

Cited by 16 publications

(11 citation statements)

References 31 publications

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“…Finally, we identified a putative Ku binding hairpin that was up to now found only in S . cerevisiae and closely related species [10,14]. In contrast, the 3‐way junction, that includes CS5 and CS6 [27], was not found.…”

Section: Resultsmentioning

confidence: 86%

“…However, sequence variability in this region is commonly observed in ciliates for which the whole telomerase structure is less conserved [26]. Finally, we identified a putative Ku binding hairpin that was up to now found only in S. cerevisiae and closely related species [10,14]. In contrast, the 3-way junction, that includes CS5 and CS6 [27], was not found.…”

Section: Secondary Structure Model Of the Telomerase Rna Of C Glabratamentioning

confidence: 78%

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Large telomerase RNA, telomere length heterogeneity and escape from senescence in Candida glabrata

Kachouri‐Lafond¹,

Dujon²,

Gilson³

et al. 2009

FEBS Letters

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Telomerase, the key enzyme essential for the maintenance of eukaryotic chromosome ends, contains a reverse transcriptase and an RNA that provides the template for the synthesis of telomeric repeats. Here, we characterize the telomerase subunits in the hemiascomycete yeast Candida glabrata. We propose a secondary structure model for the telomerase RNA that is the largest described to date. Telomerase deletion mutants show a progressive shortening of telomeres and a modest loss of viability. Frequent post-senescence survivors emerge that possess long telomeric repeat tracts. We suggest that the high telomere length heterogeneity accounts for this distinct senescence phenotype.

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Section: Resultsmentioning

confidence: 86%

Section: Secondary Structure Model Of the Telomerase Rna Of C Glabratamentioning

confidence: 78%

Large telomerase RNA, telomere length heterogeneity and escape from senescence in Candida glabrata

Kachouri‐Lafond¹,

Dujon²,

Gilson³

et al. 2009

FEBS Letters

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“…The loop connecting the two strands of the helix is shorter than those present in yeast and in one case, A. aculeatus, the template boundary forms a very short stem loop, similar in size to that formed in ciliate TERs [27]. The apical end of the arm emerging from the template boundary is known to bind the Ku protein in Saccharomyces sensu stricto and Candida glabrata [24], [69] or to contain another functional element termed Reg2 in Kluyveromyces [70], yet the arm of the Aspergillus TERs appears to be rather short, lacking any of these elements.…”

Section: Resultsmentioning

confidence: 97%

Identification of Telomerase RNAs from Filamentous Fungi Reveals Conservation with Vertebrates and Yeasts

et al. 2013

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Telomeres are the nucleoprotein complexes at eukaryotic chromosomal ends. Telomeric DNA is synthesized by the ribonucleoprotein telomerase, which comprises a telomerase reverse transcriptase (TERT) and a telomerase RNA (TER). TER contains a template for telomeric DNA synthesis. Filamentous fungi possess extremely short and tightly regulated telomeres. Although TERT is well conserved between most organisms, TER is highly divergent and thus difficult to identify. In order to identify the TER sequence, we used the unusually long telomeric repeat sequence of Aspergillus oryzae together with reverse-transcription-PCR and identified a transcribed sequence that contains the potential template within a region predicted to be single stranded. We report the discovery of TERs from twelve other related filamentous fungi using comparative genomic analysis. These TERs exhibited strong conservation with the vertebrate template sequence, and two of these potentially use the identical template as humans. We demonstrate the existence of important processing elements required for the maturation of yeast TERs such as an Sm site, a 5′ splice site and a branch point, within the newly identified TER sequences. RNA folding programs applied to the TER sequences show the presence of secondary structures necessary for telomerase activity, such as a yeast-like template boundary, pseudoknot, and a vertebrate-like three-way junction. These telomerase RNAs identified from filamentous fungi display conserved structural elements from both yeast and vertebrate TERs. These findings not only provide insights into the structure and evolution of a complex RNA but also provide molecular tools to further study telomere dynamics in filamentous fungi.

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“…KBSs are proposed to exist in both sensu stricto and sensu lato Saccharomycotina, and a putative KBS that varies in both hairpin size and sequence appears to be present in the Candida glabrata TER (Chappell and Lundblad 2004;Kachouri-Lafond et al 2009). Knockout of YKU80 in Kluyveromyces lactis does not result in a telomere-shortening phenotype, and structural modeling suggests that K. lactis TER does not contain a KBS (Brown et al 2007;Carter et al 2007;Kabaha et al 2008). Outside of the Saccharomycotina clade, KBSs have not been detected in the TERs of the fission yeast Schizosaccharomyces pombe or the filamentous ascomycete Neurospora crassa (Webb and Zakian 2008;Qi et al 2012).…”

Section: Introductionmentioning

confidence: 99%

RNA recognition by the DNA end-binding Ku heterodimer

Dalby

Goodrich

Pfingsten

et al. 2013

RNA

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Most nucleic acid-binding proteins selectively bind either DNA or RNA, but not both nucleic acids. The Saccharomyces cerevisiae Ku heterodimer is unusual in that it has two very different biologically relevant binding modes: (1) Ku is a sequence-nonspecific double-stranded DNA end-binding protein with prominent roles in nonhomologous end-joining and telomeric capping, and (2) Ku associates with a specific stem-loop of TLC1, the RNA subunit of budding yeast telomerase, and is necessary for proper nuclear localization of this ribonucleoprotein enzyme. TLC1 RNA-binding and dsDNA-binding are mutually exclusive, so they may be mediated by the same site on Ku. Although dsDNA binding by Ku is well studied, much less is known about what features of an RNA hairpin enable specific recognition by Ku. To address this question, we localized the Ku-binding site of the TLC1 hairpin with single-nucleotide resolution using phosphorothioate footprinting, used chemical modification to identify an unpredicted motif within the hairpin secondary structure, and carried out mutagenesis of the stem-loop to ascertain the critical elements within the RNA that permit Ku binding. Finally, we provide evidence that the Ku-binding site is present in additional budding yeast telomerase RNAs and discuss the possibility that RNA binding is a conserved function of the Ku heterodimer.

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The 5′ Arm of Kluyveromyces lactis Telomerase RNA Is Critical for Telomerase Function

Cited by 16 publications

References 31 publications

Large telomerase RNA, telomere length heterogeneity and escape from senescence in Candida glabrata

Large telomerase RNA, telomere length heterogeneity and escape from senescence in Candida glabrata

Identification of Telomerase RNAs from Filamentous Fungi Reveals Conservation with Vertebrates and Yeasts

RNA recognition by the DNA end-binding Ku heterodimer

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