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Flexibility of the CueR Metal Site Probed by Instantaneous Change of Element and Oxidation State from Ag I to Cd II
Author(s) -
Balogh Ria K.,
Gyurcsik Béla,
Jensen Mikael,
Thulstrup Peter W.,
Köster Ulli,
Christensen Niels Johan,
Mørch Frederik J.,
Jensen Marianne L.,
Jancsó Attila,
Hemmingsen Lars
Publication year - 2020
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.202000132
Subject(s) - chemistry , metal , crystallography , metal ions in aqueous solution , ion , ligand (biochemistry) , quadrupole , spectroscopy , stereochemistry , atomic physics , physics , receptor , biochemistry , organic chemistry , quantum mechanics
Selectivity for monovalent metal ions is an important facet of the function of the metalloregulatory protein CueR. 111 Ag perturbed angular correlation of γ‐rays (PAC) spectroscopy probes the metal site structure and the relaxation accompanying the instantaneous change from Ag I to Cd II upon 111 Ag radioactive decay. That is, a change from Ag I , which activates transcription, to Cd II , which does not. In the frozen state (−196 °C) two nuclear quadrupole interactions (NQIs) are observed; one (NQI 1 ) agrees well with two coordinating thiolates and an additional longer contact to the S77 backbone carbonyl, and the other (NQI 2 ) reflects that Cd II has attracted additional ligand(s). At 1 °C only NQI 2 is observed, demonstrating that relaxation to this structure occurs within ≈10 ns of the decay of 111 Ag. Thus, transformation from Ag I to Cd II rapidly disrupts the functional linear bis(thiolato)Ag I metal site structure. This inherent metal site flexibility may be central to CueR function, leading to remodelling into a non‐functional structure upon binding of non‐cognate metal ions. In a broader perspective, 111 Ag PAC spectroscopy may be applied to probe the flexibility of protein metal sites.