Karetsou Z, Sandaltzopoulos R, Frangou-Lazaridis M, Lai C Y, Tsolas O, Becker P B, Papamarcaki T
Laboratory of Biological Chemistry, University of Ioannina, Medical School, 451 10 Ioannina, Greece.
Nucleic Acids Res. 1998 Jul 1;26(13):3111-8. doi: 10.1093/nar/26.13.3111.
Prothymosin alpha (ProTalpha) is an abundant acidic nuclear protein that may be involved in cell proliferation. In our search for its cellular partners, we have recently found that ProTalpha binds to linker histone H1. We now provide further evidence for the physiological relevance of this interaction by immunoisolation of a histone H1-ProTalpha complex from NIH 3T3 cell extracts. A detailed analysis of the interaction between the two proteins suggests contacts between the acidic region of ProTalpha and histone H1. In the context of a physiological chromatin reconstitution reaction, the presence of ProTalpha does not affect incorporation of an amount of histone H1 sufficient to increase the nucleosome repeat length by 20 bp, but prevents association of all further H1. Consistent with this finding, a fraction of histone H1 is released when H1-containing chromatin is challenged with ProTalpha. These results imply at least two different interaction modes of H1 with chromatin, which can be distinguished by their sensitivity to ProTalpha. The properties of ProTalpha suggest a role in fine tuning the stoichiometry and/or mode of interaction of H1 with chromatin.
前胸腺素α（ProTα）是一种丰富的酸性核蛋白，可能参与细胞增殖。在寻找其细胞伴侣的过程中，我们最近发现ProTα与连接组蛋白H1结合。我们现在通过从NIH 3T3细胞提取物中免疫分离组蛋白H1-ProTα复合物，为这种相互作用的生理相关性提供了进一步的证据。对这两种蛋白质之间相互作用的详细分析表明，ProTα的酸性区域与组蛋白H1之间存在接触。在生理染色质重构反应的背景下，ProTα的存在不影响足以使核小体重复长度增加20 bp的组蛋白H1的掺入，但会阻止所有进一步的H1的结合。与此发现一致，当用ProTα处理含H1的染色质时，一部分组蛋白H1会被释放。这些结果表明H1与染色质至少存在两种不同的相互作用模式，这可以通过它们对ProTα的敏感性来区分。ProTα的特性表明其在微调H1与染色质相互作用的化学计量和/或模式方面发挥作用。
