A Solvent-Exposed Cysteine Forms a Peculiar NiII-Binding Site in the Metallochaperone CooT from Rhodospirillum rubrum

Publication

Reference: Alfano Marila, Veronesi Giulia, Musiani Francesco, Zambelli Barbara, Signor Luca, Proux Olivier, Rovezzi Mauro, Ciurli Stefano, Cavazza Christine (2019). A Solvent-Exposed Cysteine Forms a Peculiar NiII-Binding Site in the Metallochaperone CooT from Rhodospirillum rubrum. Chem. Eur. J., 25, 15351 - 15360.

Names

Title: A Solvent-Exposed Cysteine Forms a Peculiar NiII-Binding Site in the Metallochaperone CooT from Rhodospirillum rubrum
Abstract: Abstract In Rhodospirillum rubrum, the maturation of carbon monoxide dehydrogenase (CODH) requires three nickel chaperones, namely RrCooC, RrCooT and RrCooJ. Recently, the biophysical characterisation of the RrCooT homodimer and the X-ray structure of its apo form revealed the existence of a solvent-exposed NiII-binding site at the dimer interface, involving the strictly conserved Cys2. Here, a multifaceted approach that used NMR and X-ray absorption spectroscopies, complemented with structural bio-modelling methodologies, was used to characterise the binding mode of NiII in RrCooT. This study suggests that NiII adopts a square-planar geometry through a N2S2 coordinating environment that comprises the two thiolate and amidate groups of both Cys2 residues at the dimer interface. The existence of a diamagnetic mononuclear NiII centre with bis-amidate/bis-thiolate ligands, coordinated by a single-cysteine motif, is unprecedented in biology and raises the question of its role in the activation of CODH at the molecular level.
Keywords: carbon monoxide dehydrogenases, chaperone protein, CooT, enzymes, nickel, nickel-binding cysteine
Content: sample, spectral data, spectral data use

Experiment/Spectra