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Crystal structure of a eukaryotic group Ⅱ intron lariat

机译：真核生物Ⅱ类内含子套索晶体的晶体结构

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摘要

RNA剪接的第一个步骤涉及一个套索(或与套索相似的结构)在一个自催化过程中的形成。这是在一个"2′ -5′ phosophodiester"连接形成之后由内含子（intron)一端的一个切口造成的。现在，Navtej Toor及同事获得了这一分岔中间体的结构，揭示了该结构在剪接的两个步骤之间重排的详细情况。该结构的核心含有四个镁离子，它们对基质进行组织，促进套索的形成。关于一个"Group Ⅱ"内含子的这些数据也有助于了解"剪接体"（Spliceosome)的作用。%The formation of branched lariat RNA is an evolutionarily conserved feature of splicing reactions for both group Ⅱ and spliceosomal introns. The lariat is important for the fidelity of 5′ splice-site selection and consists of a2′-5′ phosphodiester bond between a bulged adenosine and the 5′ end of the intron. To gain insight into this ubiquitous intramolecular linkage, we determined the crystal structure of a eukaryotic group IIB intron in the lariat form at 3.7 A. This revealed that two tandem tetraloop-receptor interactions, η-η′ and π-π′ place domain Ⅵ in the core to position the lariat bond in the post-catalytic state. On the basis of structural and biochemical data, we propose that π-π′ is a dynamic interaction that mediates the transition between the two steps of splicing, with η-η′ serving an ancillary role. The structure also reveals a four-magnesium-ion cluster involved in both catalysis and positioning of the 5′ end. Given the evolutionary relationship between group Ⅱ and nuclear introns, it is likely that this active site configuration exists in the spliceosome as well.
机译：RNA剪接的第一个步骤涉及一个套索(或与套索相似的结构)在一个自催化过程中的形成。这是在一个"2′ -5′ phosophodiester"连接形成之后由内含子（intron)一端的一个切口造成的。现在，Navtej Toor及同事获得了这一分岔中间体的结构，揭示了该结构在剪接的两个步骤之间重排的详细情况。该结构的核心含有四个镁离子，它们对基质进行组织，促进套索的形成。关于一个"Group Ⅱ"内含子的这些数据也有助于了解"剪接体"（Spliceosome)的作用。%The formation of branched lariat RNA is an evolutionarily conserved feature of splicing reactions for both group Ⅱ and spliceosomal introns. The lariat is important for the fidelity of 5′ splice-site selection and consists of a2′-5′ phosphodiester bond between a bulged adenosine and the 5′ end of the intron. To gain insight into this ubiquitous intramolecular linkage, we determined the crystal structure of a eukaryotic group IIB intron in the lariat form at 3.7 A. This revealed that two tandem tetraloop-receptor interactions, η-η′ and π-π′ place domain Ⅵ in the core to position the lariat bond in the post-catalytic state. On the basis of structural and biochemical data, we propose that π-π′ is a dynamic interaction that mediates the transition between the two steps of splicing, with η-η′ serving an ancillary role. The structure also reveals a four-magnesium-ion cluster involved in both catalysis and positioning of the 5′ end. Given the evolutionary relationship between group Ⅱ and nuclear introns, it is likely that this active site configuration exists in the spliceosome as well.

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  • 来源
    《Nature》 |2014年第7521期|193-197a1|共6页
  • 作者

    Aaron R. Robart; Russell T. Chan; Jessica K. Peters; Kanagalaghatta R. Rajashankar; Navtej Toor;

  • 作者单位

    Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, California 92093, USA;

    Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, California 92093, USA;

    Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, California 92093, USA;

    NE-CAT and Department of Chemistry and Chemical Biology, Cornell University, Argonne National Laboratory, Argonne, Illinois 60439, USA;

    Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, California 92093, USA;

  • 收录信息 美国《科学引文索引》(SCI);美国《工程索引》(EI);美国《生物学医学文摘》(MEDLINE);美国《化学文摘》(CA);
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