CHEMICAL FOOTPRINTING OF 5S-RNA CHROMATIN IN EMBRYOS OF DROSOPHILA-MELANOGASTER
CHEMICAL FOOTPRINTING OF 5S-RNA CHROMATIN IN EMBRYOS OF DROSOPHILA-MELANOGASTER
复制标题
DOI：
10.1002/j.1460-2075.1984.tb02265.x
复制
发表时间：
1984-01-01
期刊：
影响因子：
11.4
通讯作者：
ELGIN, SCR
中科院分区：
文献类型：
--
作者：
CARTWRIGHT, IL;ELGIN, SCR
采用印迹试剂（甲丙基edta）铁（II） [MPE.cntdot.Fe(II)]对黑胃龙眼胚胎串联重复5S RNA基因的染色质结构进行了研究。对轻度MPE.cntdot.Fe（II）酶切产物的间接末端标记分析显示，每375-bp[碱基对]基因间隔单元有一个延伸的dna -蛋白复合物可接近区域。在这个跨越135 bp基因本身的区域内，一个特别高灵敏度的片段（覆盖40-60 bp）位于每个基因的远端（3”）部分。大部分基因间的非转录间隔是高度难以接近的染色质构象。这种模式在被检查的基因间隔单元的所有拷贝中重复。集群两端各15个。盐萃取实验表明，0.5 M KCl处理后图案强度降低，但在允许核小体滑动的条件下图案不会丢失。结果表明，在这些具有转录能力的5S基因中存在一种特定的、周期性的染色质结构，但这种结构是由核小体阵列以外的其他因素产生和维持的。据推测，转录复合体的蛋白质元件在观察到的结构中起主导作用。
The footprinting reagent (methidium propyl-EDTA) iron(II) [MPE.cntdot.Fe(II)] was used to investigate the chromatin structure of the tandemly repeated 5S RNA genes of D. melanogaster embryos. Indirect end-labeling analysis of the products of mild MPE.cntdot.Fe(II) digestion of nuclei reveals one extended region of accessibility of the DNA-protein complex per 375-bp [base pair] gene-spacer unit. Within this region, which spans the 135-bp gene itself, a segment of particularly high sensitivity (covering 40-60 bp) is located in the distal (3'') portion of each gene. The majority of the non-transcribed spacer between genes is in a highly inaccessible chromatin conformation. This pattern is repeated for all copies of the gene-spacer unit examined, .apprx. 15 at each end of the cluster. Salt extraction experiments show a diminution of pattern intensity after treatment with 0.5 M KCl, but the pattern is not lost under conditions which permit nucleosome sliding. The results indicate a specific, periodic chromatin structure across these transcriptionally competent 5S genes, but one which is generated and maintained by factors other than simple nucleosome arrays. Presumably protein elements of the transcription complex play a dominant role in the structure observed.