Spiegel P Clint, Chevalier Brett, Sussman Django, Turmel Monique, Lemieux Claude, Stoddard Barry L
Graduate Programs in Biomolecular Structure and Design and Molecular and Cellular Biology, University of Washington, Seattle, Washington 98195, USA.
Structure. 2006 May;14(5):869-80. doi: 10.1016/j.str.2006.03.009.
Homing endonucleases are highly specific catalysts of DNA strand breaks, leading to the transfer of mobile intervening sequences containing the endonuclease ORF. We have determined the structure and DNA recognition behavior of I-CeuI, a homodimeric LAGLIDADG endonuclease from Chlamydomonas eugametos. This symmetric endonuclease displays unique structural elaborations on its core enzyme fold, and it preferentially cleaves a highly asymmetric target site. This latter property represents an early step, prior to gene fusion, in the generation of asymmetric DNA binding platforms from homodimeric ancestors. The divergence of the sequence, structure, and target recognition behavior of homing endonucleases, as illustrated by this study, leads to the invasion of novel genomic sites by mobile introns during evolution.
归巢内切酶是DNA链断裂的高度特异性催化剂，导致含有内切酶开放阅读框的移动间隔序列的转移。我们已经确定了来自衣藻的同二聚体LAGLIDADG内切酶I-CeuI的结构和DNA识别行为。这种对称的内切酶在其核心酶折叠结构上表现出独特的结构精细之处，并且它优先切割高度不对称的靶位点。后一种特性代表了在从同二聚体祖先产生不对称DNA结合平台的过程中，在基因融合之前的早期步骤。如本研究所表明的，归巢内切酶的序列、结构和靶标识别行为的差异导致了移动内含子在进化过程中对新基因组位点的入侵。
