Theimer Carla A, Blois Craig A, Feigon Juli
Department of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles, California 90095, USA
Mol Cell. 2005 Mar 4;17(5):671-82. doi: 10.1016/j.molcel.2005.01.017.
Human telomerase contains a 451 nt RNA (hTR) and several proteins, including a specialized reverse transcriptase (hTERT). The 5' half of hTR comprises the pseudoknot (core) domain, which includes the RNA template for telomere synthesis and a highly conserved pseudoknot that is required for telomerase activity. The solution structure of this essential pseudoknot, presented here, reveals an extended triple helix surrounding the helical junction. The network of tertiary interactions explains the phylogenetic sequence conservation and existing human and mouse TR functional studies as well as mutations linked to disease. Thermodynamic stability, dimerization potential, and telomerase activity of mutant RNAs that alter the tertiary contacts were investigated. Telomerase activity is strongly correlated with tertiary structure stability, whereas there is no correlation with dimerization potential of the pseudoknot. These studies reveal that a conserved pseudoknot tertiary structure is required for telomerase activity.
人类端粒酶包含一个451个核苷酸的RNA（hTR）和几种蛋白质，包括一种特殊的逆转录酶（hTERT）。hTR的5' 端一半包含假结（核心）结构域，其中包括端粒合成的RNA模板和端粒酶活性所需的高度保守的假结。本文介绍的这种关键假结的溶液结构揭示了围绕螺旋连接的延伸三螺旋。三级相互作用网络解释了系统发育序列保守性、现有的人类和小鼠TR功能研究以及与疾病相关的突变。研究了改变三级接触的突变RNA的热力学稳定性、二聚化潜力和端粒酶活性。端粒酶活性与三级结构稳定性密切相关，而与假结的二聚化潜力无关。这些研究表明，端粒酶活性需要保守的假结三级结构。
