Dipartimento di Biologia, Università degli Studi di Napoli Federico II, 80126, Napoli, Italy.
Dipartimento di Scienze Chimiche, Università degli Studi di Napoli Federico II, 80126, Napoli, Italy.
Sci Rep. 2018 May 9;8(1):7414. doi: 10.1038/s41598-018-25784-z.
This work analyzes the involvement of arginines in copper/HO-induced DNA breakage. Copper is a highly redox active metal which has been demonstrated to form compounds with arginines. For this aim we used mixtures of pGEM3 DNA plasmid and two types of H1 histones which differ only in their arginine content. The sperm H1 histone from the annelid worm Chaetopterus variopedatus (arginine content 12.6 mol% K/R ratio 2) and the somatic H1 histone from calf thymus (arginine content 1.8 mol% and K/R ratio 15). Copper/HO-induced DNA breakage was observed only in presence of sperm H1 histones, but it was more relevant for the native molecule than for the deguanidinated derivative (K/R ratio 14), in which 80% of arginine residues were converted to ornithine. Further, copper induced proteinase K resistance and increase of DNA binding affinity on native sperm H1 histones. These observations are consistent with a copper induced reorganization of the side-chains of arginine residues. Copper, instead, did not affect DNA binding affinity of somatic and deguanidinated H1 histones, which show similar K/R ratio and DNA binding mode. These results indicate that arginine residues could affect these H1 histones properties and provide new insights into copper toxicity mechanisms.
这项工作分析了精氨酸在铜/HO 诱导的 DNA 断裂中的作用。铜是一种具有高度氧化还原活性的金属，已被证明能与精氨酸形成化合物。为此，我们使用 pGEM3 DNA 质粒和两种类型的 H1 组蛋白的混合物，这两种 H1 组蛋白仅在精氨酸含量上有所不同。环节动物 Chaetopterus variopedatus 的精子 H1 组蛋白（精氨酸含量 12.6 mol%，K/R 比 2）和小牛胸腺的体细胞 H1 组蛋白（精氨酸含量 1.8 mol%，K/R 比 15）。只有在存在精子 H1 组蛋白的情况下，才观察到铜/HO 诱导的 DNA 断裂，但对于天然分子而言，这种断裂比去胍化衍生物（K/R 比 14）更为相关，其中 80%的精氨酸残基被转化为鸟氨酸。此外，铜诱导了天然精子 H1 组蛋白的蛋白酶 K 抗性和 DNA 结合亲和力的增加。这些观察结果与铜诱导的精氨酸侧链重排一致。然而，铜并没有影响体细胞和去胍化 H1 组蛋白的 DNA 结合亲和力，它们具有相似的 K/R 比和 DNA 结合模式。这些结果表明，精氨酸残基可能影响这些 H1 组蛋白的性质，并为铜毒性机制提供新的见解。
