Gene conversion tracts stimulated by HOT1-promoted transcription are long and continuous.
Gene conversion tracts stimulated by HOT1-promoted transcription are long and continuous.
复制标题
HOT1 促进的转录刺激的基因转换束是长且连续的。
DOI：
10.1093/genetics/126.4.851
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发表时间：
1990
期刊：
影响因子：
3.3
通讯作者：
Roeder,GS
中科院分区：
文献类型：
--
作者：
Voelkel-Meiman,K;Roeder,GS
重组刺激序列HOT1与酵母RNA聚合酶i的转录启动子相对应。以携带URA3杂合基因的二倍体菌株为研究对象，研究了HOT1对有丝分裂染色体间重组的影响。当将HOT1插入到标记为URA3的染色体III拷贝中，位于URA3近端48 kbp的位置时，Ura-重组的频率增加了20倍。当HOT1和URA3位于相反的同源物上时，Ura-重组只增加了2倍。这些结果表明，大多数hot1促进的Ura-重组是由基因转换产生的，并且含有hot1的染色体上的序列优先转换。从III号染色体上携带多个标记的菌株中分离的Ura-重组体的特征表明，hot1促进的基因转化束异常长（通常大于75 kbp），并且几乎总是连续的。此外，转换束经常延伸到HOT1的两侧。我们认为HOT1促进双链断裂的形成，这通常伴随着核外溶酶切。断裂染色体的修复可以通过间隙修复或仅由含有着丝粒的染色体片段启动的复制修复来实现。
The recombination-stimulating sequence, HOT1, corresponds to the promoter of transcription by yeast RNA polymerase I. The effect of HOT1 on mitotic interchromosomal recombination was examined in diploid strains carrying a heterozygous URA3 gene on chromosome III. The frequency of Ura- recombinants was increased 20-fold when HOT1 was inserted into the chromosome III copy marked with URA3, at a location 48 kbp centromere-proximal to URA3. Ura- recombinants were increased only 2-fold when HOT1 and URA3 were on opposite homologues. These results suggest that most HOT1-promoted Ura- recombinants result from gene conversion and that sequences on the HOT1-containing chromosome are preferentially converted. Characterization of Ura- recombinants isolated from strains carrying multiple markers on chromosome III indicates that HOT1-promoted gene conversion tracts are unusually long (often greater than 75 kbp) and almost always continuous. Furthermore, conversion tracts frequently extend to both sides of HOT1. We suggest that HOT1 promotes the formation of a double-strand break which is often followed by exonucleolytic digestion. Repair of the broken chromosome could then result from gap repair or from replicative repair primed only by the centromere-containing chromosomal fragment.