Díaz-Jullien C, Pérez-Estévez A, Covelo G, Freire M
Departamento de Bioquímica y Biología Molecular, Facultad de Biología, Universidad de Santiago, Spain.
Biochim Biophys Acta. 1996 Sep 5;1296(2):219-27. doi: 10.1016/0167-4838(96)00072-6.
Prothymosin alpha (Pro Talpha) is a polypeptide which appears to be involved in cell proliferation, though its precise function has yet to be identified. Here, we report experiments which show that calf Pro Talpha selectively binds to core histones and histone H1 in vitro. Characterization of these interactions by various procedures (including affinity chromatography on Pro T alpha-Sepharose columns, immunoblotting assay and investigation of the behaviour of mixtures of Pro T alpha and histones in solution) indicated that Pro T alpha has higher affinity for core histones (particularly H3 and H4) than for H1. Similarities between the histone-binding patterns of Pro T alpha and of poly(glutamic acid) suggest that the observed histone-binding capacity resides largely in the acidic central region of Pro T alpha. However, all five histones were also bound by T alpha 1 (a peptide corresponding to the first 28 amino acids of Pro T alpha); histone binding by the N-terminal region of Pro T alpha thus cannot be ruled out. Phosphorylation of Pro T alpha does not appear to affect these interactions. In accordance with the observed capacity for histone binding, Pro T alpha (in conjunction with ATP and some Pro T alpha-binding factor/s in a thymocyte extract) was able to induce in vitro nucleosome assembly. We discuss the possibility that Pro T alpha plays a role in chromatin remodelling.
前胸腺素α（Pro Tα）是一种多肽，似乎参与细胞增殖，但其确切功能尚未确定。在此，我们报告的实验表明，小牛Pro Tα在体外能选择性地与核心组蛋白和组蛋白H1结合。通过各种方法（包括在Pro Tα-琼脂糖柱上进行亲和层析、免疫印迹分析以及研究Pro Tα与组蛋白在溶液中的混合物行为）对这些相互作用进行表征，结果表明Pro Tα对核心组蛋白（特别是H3和H4）的亲和力高于对H1的亲和力。Pro Tα与聚谷氨酸的组蛋白结合模式相似，这表明观察到的组蛋白结合能力主要存在于Pro Tα的酸性中心区域。然而，所有五种组蛋白也都能与Tα1（一种与Pro Tα的前28个氨基酸相对应的肽）结合；因此不能排除Pro Tα的N端区域与组蛋白的结合。Pro Tα的磷酸化似乎并不影响这些相互作用。根据观察到的组蛋白结合能力，Pro Tα（与ATP以及胸腺细胞提取物中的一些Pro Tα结合因子一起）能够在体外诱导核小体组装。我们讨论了Pro Tα在染色质重塑中发挥作用的可能性。
