Recently, we have studied the coordination chemistry of the Cu(II)–histidine-rich C-terminal tail (HRCT) complex of the mycobacterial GroEL1 protein. The structure of this domain differs significantly compared to the well-known methionine-glycine-rich GroEL chaperonin – it was predicted that mycobacterial GroEL1 could play a significant role in the metal homeostasis of Mycobacteria, especially copper. However, we found that this particular domain's pattern also repeats in a number of Ni(II)-binding proteins. Here, we present the studies concerning the properties of GroEL1 HRCT as a ligand for Ni(II) ions. For this purpose, we chose eight model peptides: L1 – Ac-DHDHHHGHAH, L2 – Ac-DKPAKAEDHDHHHGHAH, and 6 mutants of the latter in the pH range of 2–11. We examined the stoichiometry, stability, and spectroscopic features of copper complexes. We noticed that similar to the Cu(II)-complex, the presence of a Lys5 residue significantly increases the stability of the system. The impact of His mutations was also examined and carefully studied using NMR spectroscopy. His9 and His13 are the crucial residues for Ni(II) binding, whereas His12 has minimal relevance in complex formation.

中文翻译：

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超越铜：检查分枝杆菌 GroEL1 HRCT 中 His 突变对 Ni(II) 复合物稳定性和形成的重要性

最近，我们研究了分枝杆菌GroEL1蛋白的Cu( II )-富含组氨酸的C末端尾部(HRCT)复合物的配位化学。与众所周知的富含蛋氨酸-甘氨酸的 GroEL 伴侣蛋白相比，该结构域的结构显着不同——据预测，分枝杆菌 GroEL1 可以在分枝杆菌的金属稳态中发挥重要作用，尤其是铜。然而，我们发现这个特定结构域的模式也在许多 Ni( II ) 结合蛋白中重复。在这里，我们介绍了有关 GroEL1 HRCT 作为 Ni( II ) 离子配体的特性的研究。为此，我们选择了 8 个模型肽：L1 – Ac-DHDHHHGHAH、L2 – Ac-DKPAKAEDHDHHHGHAH，以及后者在 pH 范围为 2-11 的 6 个突变体。我们检查了铜配合物的化学计量、稳定性和光谱特征。我们注意到，与 Cu( II ) 复合物类似，Lys5 残基的存在显着提高了系统的稳定性。还使用核磁共振波谱检查和仔细研究了 His 突变的影响。 His9 和 His13 是 Ni( II ) 结合的关键残基，而 His12 在复合物形成中的相关性极小。