Est1 has the properties of a single-stranded telomere end-binding protein
Est1 has the properties of a single-stranded telomere end-binding protein
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DOI：
10.1101/gad.10.24.3094
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发表时间：
1996-12-15
影响因子：
10.5
通讯作者：
Lundblad, V
中科院分区：
文献类型：
--
作者：
VirtaPearlman, V;Morris, DK;Lundblad, V
在酿酒酵母中，EST1基因的缺失导致的表型与端粒酶的已知成分(酵母端粒酶RNA)的缺失所显示的表型相同，认为EST1也是端粒酶的关键功能。在这项研究中，我们发现EST1蛋白在体外可以与富含G的酵母端粒寡核苷酸结合。结合是单链底物所特有的，需要一个自由的3‘末端，这与蛋白质与端粒上存在的3’单链富含G的延伸部分结合的性质一致。对这种单链DNA结合蛋白在体内的功能评估表明，EST1与TLC1端粒酶RNA在相同的端粒复制途径中发挥作用，通过几个不同的遗传标准：EST1 tlc1双突变株相对于任何一个突变株都没有表现出表型增强，EST1显性突变对端粒沉默的影响与TLC1以前所显示的相似。我们认为EST1是一种端粒末端结合蛋白，它是通过端粒酶介导染色体末端识别所必需的。
In Saccharomyces cerevisiae, deletion of the EST1 gene results in phenotypes identical to those displayed by a deletion of a known component of telomerase (the yeast telomerase RNA), arguing that EST1 is also critical far telomerase function. In this study, we show that the Est1 protein binds to yeast G-rich telomeric oligonucleotides in vitro. Binding is specific for single-stranded substrates and requires a free 3' terminus, consistent with the properties expected for a protein bound to the 3' single-stranded G-rich extension present at the telomere. Assessment of the in vivo function of this single-stranded DNA-binding protein has shown that EST1 acts in the same pathway of telomere replication as the TLC1 telomerase RNA, by several different genetic criteria: est1 tlc1 double mutant strains show no enhancement of phenotype relative to either single mutant strain, and EST1 dominant mutations have an effect on telomeric silencing similar to that displayed by TLC1 previously. We propose that Est1 is a telomere end-binding protein that is required to mediate recognition of the end of the chromosome by telomerase.