Department of Inorganic and Analytical Chemistry, University of Szeged, Dóm tér 7, 6720, Szeged, Hungary.
Laboratory of Proteomics Research, Institute of Biochemistry, Biological Research Centre of the Hungarian Academy of Sciences, Temesvári krt. 62, 6726, Szeged, Hungary.
Chemistry. 2019 Nov 27;25(66):15030-15035. doi: 10.1002/chem.201902940. Epub 2019 Oct 15.
Intracellular Cu is controlled by the transcriptional regulator CueR, which effectively discriminates between monovalent and divalent metal ions. It is intriguing that Hg does not activate transcription, as bis-thiolate metal sites exhibit high affinity for Hg . Here the binding of Hg to CueR and a truncated variant, ΔC7-CueR, without the last 7 amino acids at the C-terminus including a conserved CCHH motif is explored. ESI-MS demonstrates that up to two Hg bind to CueR, while ΔC7-CueR accommodates only one Hg . Hg PAC and UV absorption spectroscopy indicate HgS structure at both the functional and the CCHH metal site. However, at sub-equimolar concentrations of Hg at pH 8.0, the metal binding site displays an equilibrium between HgS and HgS , involving cysteines from both sites. We hypothesize that the C-terminal CCHH motif provides auxiliary ligands that coordinate to Hg and thereby prevents activation of transcription.
细胞内的 Cu 受到转录调节因子 CueR 的控制，CueR 可以有效地将单价和二价金属离子区分开来。有趣的是，Hg 不能激活转录，因为双硫代金属位点对 Hg 表现出高亲和力。在这里，研究了 Hg 与 CueR 和一个截断的变体 ΔC7-CueR 的结合，该变体在 C 端缺少最后 7 个氨基酸，包括保守的 CCHH 基序。ESI-MS 表明，CueR 可以结合多达两个 Hg，而 ΔC7-CueR 只能结合一个 Hg。HgPAC 和紫外吸收光谱表明，在功能和 CCHH 金属位点都形成了 HgS 结构。然而，在 pH 值为 8.0 时，亚等摩尔浓度的 Hg 存在于金属结合位点，HgS 和 HgS 之间存在平衡，涉及两个位点的半胱氨酸。我们假设 C 端的 CCHH 基序提供辅助配体，与 Hg 配位，从而防止转录激活。
