起始识别复合物结合位点对沉默子的辅助作用

Auxiliary role of origin recognition complex binding site for silencer involved in transcriptional silencing

背景:沉默子由起始识别复合物结合位点,阻遏活化蛋白RAP1等元件组成,人们对于沉默子的功能及相互关系有较多研究,但对组成沉默子的元件与基因沉默之间关系的研究很少。目的:研究起始识别复合物结合位点对沉默子基因沉默的辅助作用。方法:用右侧带有报告基因URA3的起始识别复合物结合位点,以及不带任何结合位点的序列替代酵母基因组HML区域的HML-I沉默子后,比较URA3基因表达量,并使用DNA拓扑法分析染色质的结构变化。结果与结论:HML-E沉默子单独存在的情况下,酵母无法在FOA平板上生长,但在起始识别复合物结合位点的辅助下,能够在FOA平板上生长,两者之间区域的染色质大多为负超螺旋。因此可知起始识别复合物结合位点能增加HML-E沉默子作用范围,产生这种作用的原因是两者相互作用下形成紧密的染色质结构。

BACKGROUND：Silencer is consisted of origin recognition complex（ORC）,RAP1 and other elements.There were a lot of reports on function and relationship between silencers but few researches concerning silencer elements.OBJECTIVE：To study the auxiliary gene silencing effect of ORC to silencer.METHODS：Delete or replace HML-I silencer with ORC binding site with URA3 in the right side or blank sequence without any binding sites to compare expression level of URA3 and analyze the difference of chromatin structure with DNA topological method.RESULTS AND CONCLUSION：When HML-E silencer exited alone,yeast could not grow on FOA plates.But with auxiliary effect of ORC binding site,it was able to grow on the FOA plate,and the proportion of negative super coiled DNA was larger compared with that in the case that HML-E silencer exits alone.Therefore,ORC can interact with HML-E to condense the chromatin structure and enhance gene silencing.