Li B, Adams C C, Workman J L
Department of Biochemistry and Molecular Biology, Pennsylvania State University, University Park 16802-4500.
J Biol Chem. 1994 Mar 11;269(10):7756-63.
The constitutive transcription factor Sp1 plays a role in the transcription of numerous viral and cellular genes including constitutive "housekeeping" genes and inducible genes. Sp1 has also been implicated in the formation of a nucleosome-free region in Simian virus 40 (SV40) minichromosomes. To investigate the potential functions of Sp1 in remodeling chromatin structures, Sp1 was analyzed for the ability to bind its recognition sites (GC boxes) in DNA fragments reconstituted into nucleosome cores. Sp1 was found to bind to the GC boxes of the SV40 early promoter when this element was reconstituted into nucleosome cores. The affinity of Sp1 for the nucleosomal SV40 early promoter DNA was reduced approximately 10-20-fold relative to naked DNA. A peptide containing only the zinc fingers of Sp1 was also capable of binding nucleosomal DNA, indicating that the glutamine-rich and serine/threonine-rich domains of Sp1 are not required for nucleosome binding. The binding of Sp1 to nucleosome cores resulted in the formation of a ternary Sp1-nucleosome complex.
组成型转录因子Sp1在众多病毒和细胞基因的转录中发挥作用，这些基因包括组成型“管家”基因和诱导型基因。Sp1还与猿猴病毒40（SV40）微型染色体中无核小体区域的形成有关。为了研究Sp1在重塑染色质结构中的潜在功能，分析了Sp1在重构入核小体核心的DNA片段中结合其识别位点（GC盒）的能力。当SV40早期启动子元件重构入核小体核心时，发现Sp1能与之结合。相对于裸露DNA，Sp1对核小体SV40早期启动子DNA的亲和力降低了约10至20倍。仅含Sp1锌指的肽也能够结合核小体DNA，这表明Sp1富含谷氨酰胺和富含丝氨酸/苏氨酸的结构域对于核小体结合并非必需。Sp1与核小体核心的结合导致形成三元Sp1-核小体复合物。
