A structurally conserved human and Tetrahymena telomerase catalytic core
A structurally conserved human and Tetrahymena telomerase catalytic core
复制标题
DOI：
10.1073/pnas.2011684117
复制
发表时间：
2020-11
期刊：
影响因子：
--
通讯作者：
Yaqiang Wang;M. Gallagher-Jones;L. Sušac;He Song;J. Feigon
中科院分区：
文献类型：
--
作者：
Yaqiang Wang;M. Gallagher-Jones;L. Sušac;He Song;J. Feigon
端粒酶逆转录酶（telomerase reverse transcriptase，TERT）是逆转录酶中的一种，它具有重复利用自身RNA模板补充染色体末端DNA重复序列的独特能力。TERT与其他逆转录酶以及端粒酶特异性基序/结构域共享多种共同特征。其中，TEN和TRAP并不明显地存在于所有注释的TERT序列中，但它们在四膜虫端粒酶中形成了端粒酶独特活性所必需的复合物。使用生物信息学和结构分析，我们表明，TEN和TRAP共同进化，并提出他们的定义功能的TERT。我们提出了一个适合于已发表的冷冻电子显微镜图的人类端粒酶模型，这将有助于研究与疾病相关的机制、招募和突变。端粒酶是一种核糖核蛋白复合物，它可以抵消由于不完全复制而导致的染色体末端缩短。端粒酶是由端粒酶逆转录酶（telomerase reverse transcriptase，TERT）和端粒酶RNA（telomerase RNA，TER）组成的催化核心。然而，什么定义了TERT并将其与其他逆转录酶区分开来仍然是一个争论的主题。最近的四膜虫端粒酶冷冻电子显微镜图揭示了以前未表征的TERT结构域（TRAP）的结构，该结构域与端粒酶必需N末端（TEN）结构域发生了意想不到的相互作用，并在端粒酶活性中发挥了作用。TEN和TRAP都不存在于推定的赤拟谷盗属（Tribolium）TERT中，该TERT已被用作端粒酶的模型超过十年。为了研究TRAP和TEN跨物种的保守性，我们对所有鉴定的TERTs进行了多重序列比对和统计偶联分析，发现TEN和TRAP作为端粒酶特异性结构域共同进化。综合生物信息学分析的数据和四膜虫端粒酶的结构，我们建立了一个人端粒酶催化核心的假原子模型，该模型几乎占了已发表地图中所有的冷冻电子显微镜密度，包括TRAP在以前未分配的密度以及端粒酶RNA结构域的活性。这个更完整的人类端粒酶催化核心模型说明了TER和TERT的结构域，包括TEN-TRAP复合物，如何以保守的方式相互作用以调节端粒合成。
Significance Among reverse transcriptases, telomerase reverse transcriptase (TERT) has the unique ability to replenish DNA repeats at chromosome ends by repetitively using its integral RNA template. TERT shares a variety of common features with other reverse transcriptases as well as telomerase-specific motifs/domains. Among them, TEN and TRAP are not obviously present in all annotated TERT sequences, yet they form a complex in Tetrahymena telomerase that is essential for telomerase’ distinctive activities. Using bioinformatic and structural analysis we show that TEN and TRAP have coevolved and propose that they are defining features of TERT. We present a model for human telomerase that fits into the published cryoelectron microscopy map that will facilitate studies of mechanism, recruitment, and mutations linked to disease. Telomerase is a ribonucleoprotein complex that counteracts the shortening of chromosome ends due to incomplete replication. Telomerase contains a catalytic core of telomerase reverse transcriptase (TERT) and telomerase RNA (TER). However, what defines TERT and separates it from other reverse transcriptases remains a subject of debate. A recent cryoelectron microscopy map of Tetrahymena telomerase revealed the structure of a previously uncharacterized TERT domain (TRAP) with unanticipated interactions with the telomerase essential N-terminal (TEN) domain and roles in telomerase activity. Both TEN and TRAP are absent in the putative Tribolium TERT that has been used as a model for telomerase for over a decade. To investigate the conservation of TRAP and TEN across species, we performed multiple sequence alignments and statistical coupling analysis on all identified TERTs and find that TEN and TRAP have coevolved as telomerase-specific domains. Integrating the data from bioinformatic analysis and the structure of Tetrahymena telomerase, we built a pseudoatomic model of human telomerase catalytic core that accounts for almost all of the cryoelectron microscopy density in a published map, including TRAP in previously unassigned density as well as telomerase RNA domains essential for activity. This more complete model of the human telomerase catalytic core illustrates how domains of TER and TERT, including the TEN–TRAP complex, can interact in a conserved manner to regulate telomere synthesis.