Banerjee Sourav, Kundu Tapas K
Transcription and Disease Laboratory, Molecular Biology and Genetics Unit, Jawaharlal Nehru Center for Advanced Scientific Research, Jakkur, Bangalore 560064, India.
Nucleic Acids Res. 2003 Jun 15;31(12):3236-47. doi: 10.1093/nar/gkg412.
p53 function is modulated by several covalent and non-covalent modifiers. The architectural DNA- binding protein, High Mobility Group protein B-1 is a unique activator of p53. HMGB-1 protein is structured into two HMG-box domains, namely A-box and B-box, connected to a long highly acidic C-terminal domain. Here we report that both the C-terminal domain and A-box of HMGB-1 are critical for stimulation of p53-mediated DNA binding to its cognate site. Though deletion of these domains showed minimal effect in activation of p53-mediated transcription from the DNA template as compared to full-length HMGB-1, truncation of both the domains indeed showed significant reduction of transcriptional activation from the chromatin template as observed in DNA binding. Using transient transfection assays we showed that the C-terminal acidic domain and A-box of HMGB-1 are critical for the enhancement of the p53-mediated transactivation in vivo. Furthermore, the C-terminal domain and A-box deleted HMGB-1 could not activate p53-dependent apoptosis above the basal level. In conclusion, these results elucidate the role of acidic C-terminal domain and A-box of HMGB-1 in p53-mediated transcriptional activation and its further downstream effect.
p53的功能受到多种共价和非共价修饰剂的调节。结构型DNA结合蛋白高迁移率族蛋白B-1（HMGB-1）是p53的一种独特激活剂。HMGB-1蛋白由两个HMG盒结构域组成，即A盒和B盒，连接到一个长的高度酸性的C末端结构域。在此我们报告，HMGB-1的C末端结构域和A盒对于刺激p53介导的DNA与其同源位点的结合至关重要。尽管与全长HMGB-1相比，缺失这些结构域对p53介导的从DNA模板转录激活的影响最小，但如在DNA结合中所观察到的，这两个结构域的截短确实显示出从染色质模板转录激活的显著降低。使用瞬时转染实验我们表明，HMGB-1的C末端酸性结构域和A盒对于增强体内p53介导的反式激活至关重要。此外，缺失C末端结构域和A盒的HMGB-1在基础水平之上不能激活p53依赖性凋亡。总之，这些结果阐明了HMGB-1的酸性C末端结构域和A盒在p53介导的转录激活及其进一步下游效应中的作用。
