DNA DAMAGE ACTIVATES TRANSCRIPTION AND TRANSPOSITION OF YEAST TY RETROTRANSPOSONS
DNA DAMAGE ACTIVATES TRANSCRIPTION AND TRANSPOSITION OF YEAST TY RETROTRANSPOSONS
复制标题
DOI：
10.1007/bf00332411
复制
发表时间：
1989-09-01
期刊：
影响因子：
--
通讯作者：
MCENTEE, K
中科院分区：
文献类型：
--
作者：
BRADSHAW, VA;MCENTEE, K
从酿酒酵母中分离出的一组基因显示，酵母在紫外线(UV)或4-硝基喹啉-1-氧化物(4NQO)照射后，转录水平增加。在这些DNA损伤反应(DDR)基因中包括酵母的Ty反转录转座子家族的成员。Northern杂交分析表明，在4NQO作用4~6h后，Ty元件编码的5.6kb转录本在细胞内达到最高水平。不同TY探针诱导的转录本水平从2倍到10倍不等，但与不同TY家族成员杂交的转录本具有相似的动力学和剂量反应。脉冲标记实验表明，Ty转录本的积累部分是由于Ty信息合成速度的增加。在暴露于剂量增加的紫外光或4NQO的细胞中，研究了Ty元件到编码不同酒精脱氢酶的两个靶基因ADH2和ADH4的转位。在DNA损伤处理后，Ty插入这些遗传区域的频率比未处理的细胞增加了17倍。这些结果提供了直接证据，表明转座元件可以被物理和化学诱变剂/致癌物激活，并在酿酒酵母中由这些诱变剂诱导转座突变。
A set of genes isolated from Saccharomyces cerevisiae showed increased transcript levels after yeast had been exposed to ultraviolet (UV) light or 4-nitroquinoline-1-oxide (4NQO). Included among these DNA damage responsive (DDR) genes were members of the Ty retrotransposon family of yeast. Northern hybridization analysis indicated that maximal levels of a 5.6 kb transcript encoded by the Ty elements accumulated in cells after 4 to 6 h of exposure to 4NQO. The induced levels of transcripts varied from two- to tenfold for different Ty probes although similar kinetics and dose responses were observed for transcripts hybridizing to the different Ty family members. Pulse labeling experiments suggested that the accumulation of Ty transcripts was due, in part, to an increased rate of Ty message synthesis. Transposition of Ty elements to two target loci encoding distinct alcohol dehydrogenase enzymes, ADH2 and ADH4, was examined in cells exposed to increasing doses of UV light or 4NQO. The frequency of Ty insertion into these genetic regions following DNA damaging treatments increased by as much as 17-fold compared with untreated cells. These results provide direct evidence that transposable elements can be activated by physical and chemical mutagens/carcinogens and that transpositional mutagenesis is induced by these agents in S. cerevisiae.