Intronless homing: site-specific endonuclease SegF of bacteriophage T4 mediates localized marker exclusion analogous to homing endonucleases of group I introns
Intronless homing: site-specific endonuclease SegF of bacteriophage T4 mediates localized marker exclusion analogous to homing endonucleases of group I introns
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DOI：
10.1101/gad.960302
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发表时间：
2002-02-01
影响因子：
10.5
通讯作者：
Shub, DA
中科院分区：
文献类型：
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作者：
Belle, A;Landthaler, M;Shub, DA
来自噬菌体T2的所有遗传标记部分地从与相关噬菌体T4的混合感染的后代中排除（一般或噬菌体排除）。几个位点，包括T2的基因56，更显着地被排除在外，仅存在于约1%的后代中。这种现象被称为局部标记排除。基因69与T4的基因56相邻，但在T2中不存在，被完全非同源的DNA取代。我们描述了SegF，一种新的由基因69编码的位点特异性DNA内切酶，它类似于I组内含子的GIY-YIG归巢内切酶。有趣的是，与噬菌体T4相比，SegF在体外和体内都优先切割T2的基因56。双链断裂（DSB）的修复导致子代中T4基因56和segF占优势，排除相应的T2序列。T2基因56的局部排除依赖于全长SegF，并且可能类似于I组内含子归巢，其中DSB的修复导致侧翼DNA中标记的共转换。噬菌体T4具有许多类似于segF的可选归巢核酸内切酶基因，而类似的核酸内切酶基因在噬菌体的T-even家族的其他成员中相对罕见。我们建议，T4噬菌体所享有的一般优势，几乎所有的亲戚，是许多这些本地化的事件的累积效应。
All genetic markers from phage T2 are partially excluded from the progeny of mixed infections with the related phage T4 (general, or phage exclusion). Several loci, including gene 56 of T2, are more dramatically excluded, being present in only similar to1% of the progeny. This phenomenon is referred to as localized marker exclusion. Gene 69 is adjacent to gene 56 of T4 but is absent in T2, being replaced by completely nonhomologous DNA. We describe SegF, a novel site-specific DNA endonuclease encoded by gene 69, which is similar to GIY-YIG homing endonucleases of group I introns. Interestingly, SegF preferentially cleaves gene 56 of T2, both in vitro and in vivo, compared with that of phage T4. Repair of the double-strand break (DSB) results in the predominance of T4 genes 56 and segF in the progeny, with exclusion of the corresponding T2 sequences. Localized exclusion of T2 gene 56 is dependent on full-length SegF and is likely analogous to group I intron homing, in which repair of a DSB results in coconversion of markers in the flanking DNA. Phage T4 has many optional homing endonuclease genes similar to segF, whereas similar endonuclease genes are relatively rare in other members of the T-even family of bacteriophages. We propose that the general advantage enjoyed by T4 phage, over almost all of its relatives, is a cumulative effect of many of these localized events.