Biophysical and structural characterization of the putative nickel chaperone CooT from Carboxydothermus hydrogenoformans

August 13, 2018

Title

Biophysical and structural characterization of the putative nickel chaperone CooT from Carboxydothermus hydrogenoformans

Author

M. Alfano, J. Pérard, R. Miras, P. Catty, C. Cavazza

Year

2018

Journal

Journal of Biological Inorganic Chemistry

Abstract

Carboxydothermus hydrogenoformans is a model microorganism for the study of [NiFe]–CODH, a key enzyme of carbon cycle in anaerobic microorganisms. The enzyme possesses a unique active site (C-cluster), constituted of a distorted [NiFe3S4] cubane linked to a mononuclear Fe(II) center. Both the biogenesis of the C-cluster and the activation of CODH by nickel insertion remain unclear. Among the three accessory proteins thought to play a role in this latter step (CooC, CooJ, and CooT), CooT is identified as a nickel chaperone involved in CODH maturation in Rhodospirillum rubrum. Here, we structurally and biophysically characterized a putative CooT protein present in C. hydrogenoformans (pChCooT). Despite the low sequence homologies between CooT from R. rubrum (RrCooT) and pChCooT (19% sequence identity), the two proteins share several similarities, such as their overall structure and a solvent-exposed Ni(II)-binding site at the dimer interface. Moreover, the X-ray structure of pChCooT reveals the proximity between the histidine 55, a potential nickel-coordinating residue, and the cysteine 2, a highly conserved key residue in Ni(II)-binding.

Instrument

J-1500

Keywords

Circular dichroism, Secondary structure, Chemical stability, Ligand binding, Tertiary structure, Visible region, Biochemistry, Inorganic chemistry