Coevolution of a homing endonuclease and its host target sequence
Coevolution of a homing endonuclease and its host target sequence
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DOI：
10.1016/j.jmb.2007.07.052
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发表时间：
2007-10-05
影响因子：
5.6
通讯作者：
Stoddard, Barry L.
中科院分区：
文献类型：
--
作者：
Scalley-Kim, Michelle;McConnell-Smith, Audrey;Stoddard, Barry L.
我们已经确定了归巢核酸内切酶 I-Anil 的特异性特征，并将其与其宿主基因的保守性进行了比较。归巢核酸内切酶在插入序列（例如 I 组内含子）内编码。它们通过切割缺乏内含子的同源等位基因来启动这些元件的转移，从而导致它们通过同源的特异性和保真度适当平衡的转移，避免毒性，同时最大化目标识别和侵袭性。 I-Anil 识别编码脱辅基细胞色素 B 的宿主基因中高度保守的靶序列，并对其特异性进行了微调，以与该序列中的摆动与非摆动位置以及单个密码子固有的简并性量相关。宿主基因中的生理目标位点并不是识别和切割的最佳底物：在筛选过程中鉴定出的至少一种目标变体结合得更紧密并且切割得更快。这是内含子归巢周期性循环的结果，内含子归巢在任何时候都可能在生物宿主中呈现内切核酸酶特异性和插入位点序列的非最佳组合。 (c) 2007 Elsevier Ltd. 保留所有权利。
We have determined the specificity profile of the homing endonuclease I-Anil and compared it to the conservation of its host gene. Homing endonucleases are encoded within intervening sequences such as group I introns. They initiate the transfer of such elements by cleaving cognate alleles lacking the intron, leading to their transfer via homologous at an appropriate balance of specificity and fidelity that avoids toxicity while maximizing target recognition and invasiveness. I-Anil recognizes a strongly conserved target sequence in a host gene encoding apocytochrome B and has fine-tuned its specificity to correlate with wobble versus non-wobble positions across that sequence and to the amount of degeneracy inherent in individual codons. The physiological target site in the host gene is not the optimal substrate for recognition and cleavage: at least one target variant identified during a screen is bound more tightly and cleaved more rapidly. This is a result of the periodic cycle of intron homing, which at any time can present nonoptimal combinations of endonuclease specificity and insertion site sequences in a biological host. (c) 2007 Elsevier Ltd. All rights reserved.