Research Program in Structural Biology and Biophysics, Institute of Biotechnology, University of Helsinki, P.O. Box 65, 00014, Helsinki, Finland.
Extremophiles. 2019 Nov;23(6):669-679. doi: 10.1007/s00792-019-01117-4. Epub 2019 Jul 30.
Self-splicing inteins are mobile genetic elements invading host genes via nested homing endonuclease (HEN) domains. All HEN domains residing within inteins are inserted at a highly conserved insertion site. A purifying selection mechanism directing the location of the HEN insertion site has not yet been identified. In this work, we solved the three-dimensional crystal structures of two inteins inserted in the cell division control protein 21 of the hyperthermophilic archaea Pyrococcus abyssi and Pyrococcus horikoshii. A comparison between the structures provides the structural basis for the thermo-stabilization mechanism of inteins that have lost the HEN domain during evolution. The presence of an entire extein domain in the intein structure from Pyrococcus horikoshii suggests the selection mechanism for the highly conserved HEN insertion point.
自身剪接内含子是通过嵌套同源内切酶 (HEN) 结构域入侵宿主基因的移动遗传元件。所有位于内含子内的 HEN 结构域都插入到高度保守的插入位点。尚未确定指导 HEN 插入位点位置的纯化选择机制。在这项工作中，我们解决了两个内含子在超嗜热古菌 Pyrococcus abyssi 和 Pyrococcus horikoshii 的细胞分裂控制蛋白 21 中的插入的三维晶体结构。结构之间的比较为在进化过程中失去 HEN 结构域的内含子的热稳定化机制提供了结构基础。来自 Pyrococcus horikoshii 的内含子结构中存在完整的外显子结构，这表明了高度保守的 HEN 插入点的选择机制。
