Gargiulo G, Razvi F, Ruberti I, Mohr I, Worcel A
J Mol Biol. 1985 Feb 5;181(3):333-49. doi: 10.1016/0022-2836(85)90223-2.
A cloned histone H4 gene of Xenopus laevis is efficiently transcribed after injection into germinal vesicles of X. laevis oocytes. Deletion analyses indicate that less than 140 base-pairs of 5' flanking sequences and 50 base-pairs of 3' flanking sequences are required for efficient transcription of this gene in Xenopus oocytes. Chromatin footprint analysis by a direct end-label technique reveals discrete DNase I-hypersensitive and micrococcal nuclease-hypersensitive sites at the 5' and 3' boundaries of the gene, which bracket the transcribed region of this minichromosome. The specific chromatin structure assembled around this homologous gene, together with the finding that histone genes of Drosophila melanogaster are not assembled into specific nucleoprotein structures within Xenopus oocytes, strongly suggest that sequence-specific and species-specific factors may be responsible for generating the chromatin-specific hypersensitive sites at the boundaries of active genes.
非洲爪蟾的一个克隆组蛋白H4基因在注入非洲爪蟾卵母细胞的生发泡后能高效转录。缺失分析表明，该基因在非洲爪蟾卵母细胞中高效转录所需的5'侧翼序列少于140个碱基对，3'侧翼序列少于50个碱基对。通过直接末端标记技术进行的染色质足迹分析揭示了该基因5'和3'边界处离散的脱氧核糖核酸酶I超敏和微球菌核酸酶超敏位点，这些位点包围了这个微型染色体的转录区域。围绕这个同源基因组装的特定染色质结构，以及黑腹果蝇的组蛋白基因在非洲爪蟾卵母细胞中未组装成特定核蛋白结构这一发现，强烈表明序列特异性和物种特异性因素可能是在活性基因边界产生染色质特异性超敏位点的原因。
