Est1 has the properties of a single-stranded telomere end-binding protein.

Virta-Pearlman, V J; Morris, Danna K.; Lundblad, Victoria

doi:10.1101/gad.10.24.3094

Cited by 144 publications

(178 citation statements)

References 58 publications

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“…EST2 and TLC1 encode the reverse transcriptase catalytic protein subunit and the templating RNA, respectively 9,11,12 . In addition, the protein encoded by EST1 is associated with the RNA component of telomerase, TLC1 (refs [13][14][15][16]. Other accessory factors, such as Cdc13, are required for the in vivo action of telomerase.…”

mentioning

confidence: 99%

PP2A and Aurora differentially modify Cdc13 to promote telomerase release from telomeres at G2/M phase

Shen

Hsu

et al. 2014

Nat Commun

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In yeast, the initiation of telomere replication at the late S phase involves in combined actions of kinases on Cdc13, the telomere binding protein. Cdc13 recruits telomerase to telomeres through its interaction with Est1, a component of telomerase. However, how cells terminate the function of telomerase at G2/M is still elusive. Here we show that the protein phosphatase 2A (PP2A) subunit Pph22 and the yeast Aurora kinase homologue Ipl1 coordinately inhibit telomerase at G2/M by dephosphorylating and phosphorylating the telomerase recruitment domain of Cdc13, respectively. While Pph22 removes Tel1/Mec1-mediated Cdc13 phosphorylation to reduce Cdc13-Est1 interaction, Ipl1-dependent Cdc13 phosphorylation elicits dissociation of Est1-TLC1, the template RNA component of telomerase. Failure of these regulations prevents telomerase from departing telomeres, causing perturbed telomere lengthening and prolonged M phase. Together our results demonstrate that differential and additive actions of PP2A and Aurora on Cdc13 limit telomerase action by removing active telomerase from telomeres at G2/M phase.

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mentioning

confidence: 99%

PP2A and Aurora differentially modify Cdc13 to promote telomerase release from telomeres at G2/M phase

Shen

Hsu

et al. 2014

Nat Commun

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“…1). The variation in RNA affinity relative to a prior report likely reflects the use of different RNA probes (9). The Est1 RNA binding was dependent upon the bulged-stem loop structure, as a disrupted-stem RNA displayed no apparent interaction and a bulge-delete RNA had a decreased affinity (K d Ϸ300 nM).…”

Section: Est1mentioning

confidence: 80%

“…The initial Est1 biochemical characterization demonstrated that the protein preferentially binds DNAs with 3Ј single-stranded G-rich sequence (9). We wished to extend these observations by delineating the DNA length requirements for Est1 binding.…”

Section: Est1mentioning

confidence: 99%

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The conserved Est1 protein stimulates telomerase DNA extension activity

DeZwaan

Freeman

2009

Proc. Natl. Acad. Sci. U.S.A.

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The first telomerase cofactor identified was the budding yeast protein Est1, which is conserved through humans. While it is evident that Est1 is required for telomere DNA maintenance, understanding its mechanistic contributions to telomerase regulation has been limited. In vitro, the primary effect of Est1 is to activate telomerase-mediated DNA extension. Although Est1 displayed specific DNA and RNA binding, neither activity contributed significantly to telomerase stimulation. Rather Est1 mediated telomerase upregulation through direct contacts with the reverse transcriptase subunit. In addition to intrinsic Est1 functions, we found that Est1 cooperatively activated telomerase in conjunction with Cdc13 and that the combinatorial effect was dependent upon a known salt-bridge interaction between Est1 (K444) and Cdc13 (E252). Our studies provide insights into the molecular events used to control the enzymatic activity of the telomerase holoenzyme.telomere biology ͉ telomerase regulation

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“…In addition to Cdc13p, several proteins with single-stranded telomeric DNA-binding activities have been identified in yeast [16][17][18][19]. Est1p is a telomerase-associated protein that mediates the binding of telomerase to telomeres [13].…”

Section: Introductionmentioning

confidence: 99%

The U3 small nucleolar ribonucleoprotein component Imp4p is a telomeric DNA-binding protein

Hsieh¹,

Tu²,

Lee³

et al. 2007

Biochemical Journal

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Imp4p is a component of U3 snoRNP (small nucleolar ribonucleoprotein) involved in the maturation of 18S rRNA. We have shown that Imp4p interacts with Cdc13p, a single-stranded telomere-binding protein involved in telomere maintenance. To understand the role of Imp4p in telomeres, we purified recombinant Imp4p protein and tested its binding activity towards telomeric DNA using electrophoretic mobility-shift assays. Our results showed that Imp4p bound specifically to single-stranded telomeric DNA in vitro. The interaction of Imp4p to telomeres in vivo was also demonstrated by chromatin immunoprecipitation experiments. Significantly, the binding of Imp4p to telomeres was not limited to yeast proteins, since the hImp4 (human Imp4) also bound to vertebrate single-stranded telomeric DNA. Thus we conclude that Imp4p is a novel telomeric DNA-binding protein that, in addition to its role in rRNA processing, might participate in telomere function.

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Est1 has the properties of a single-stranded telomere end-binding protein.

Cited by 144 publications

References 58 publications

PP2A and Aurora differentially modify Cdc13 to promote telomerase release from telomeres at G2/M phase

PP2A and Aurora differentially modify Cdc13 to promote telomerase release from telomeres at G2/M phase

The conserved Est1 protein stimulates telomerase DNA extension activity

The U3 small nucleolar ribonucleoprotein component Imp4p is a telomeric DNA-binding protein

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