C-terminal Cysteines of CueR Act as Auxiliary Metal Site Ligands upon HgII Binding—A Mechanism To Prevent Transcriptional Activation by Divalent Metal Ions?
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- C‐terminal Cysteines of CueR Act as Auxiliary Metal Site Ligands
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Intracellular CuI is controlled by the transcriptional regulator CueR, which effectively discriminates between monovalent and divalent metal ions. It is intriguing that HgII does not activate transcription, as bis-thiolate metal sites exhibit high affinity for HgII. Here the binding of HgII 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 HgII bind to CueR, while ΔC7-CueR accommodates only one HgII. 199mHg PAC and UV absorption spectroscopy indicate HgS2 structure at both the functional and the CCHH metal site. However, at sub-equimolar concentrations of HgII at pH 8.0, the metal binding site displays an equilibrium between HgS2 and HgS3, involving cysteines from both sites. We hypothesize that the C-terminal CCHH motif provides auxiliary ligands that coordinate to HgII and thereby prevents activation of transcription.
Originalsprog | Engelsk |
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Tidsskrift | Chemistry - A European Journal |
Vol/bind | 25 |
Udgave nummer | 66 |
Sider (fra-til) | 15030–15035 |
Antal sider | 6 |
ISSN | 0947-6539 |
DOI | |
Status | Udgivet - 2019 |
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ID: 231413441