Publication
Names
  • S. Morante
  • S. Botticelli
  • R. Chiaraluce
  • V. Consalvi
  • G. La Penna
  • L. Novak
  • A. Pasquo
  • M. Petrosino
  • O. Proux
  • G. Rossi
  • G. Salina
  • F. Stellato
Title
Metal Ion Binding in Wild-Type and Mutated Frataxin: A Stability Study
Abstract
This work studies the stability of wild-type frataxin and some of its variants found in cancer tissues upon Co2+ binding. Although the physiologically involved metal ion in the frataxin enzymatic activity is Fe2+, as it is customarily done, Co2+ is most often used in experiments because Fe2+ is extremely unstable owing to the fast oxidation reaction Fe2+ → Fe3+. Protein stability is monitored following the conformational changes induced by Co2+ binding as measured by circular dichroism, fluorescence spectroscopy, and melting temperature measurements. The stability ranking among the wild-type frataxin and its variants obtained in this way is confirmed by a detailed comparative analysis of the XAS spectra of the metal-protein complex at the Co K-edge. In particular, a fit to the EXAFS region of the spectrum allows positively identifying the frataxin acidic ridge as the most likely location of the metal-binding sites. Furthermore, we can explain the surprising feature emerging from a detailed analysis of the XANES region of the spectrum, showing that the longer 81-210 frataxin fragment has a smaller propensity for Co2+ binding than the shorter 90-210 one. This fact is explained by the peculiar role of the N-terminal disordered tail in modulating the protein ability to interact with the metal.
Keywords
spectroscopy
Content
sample, experimental physics, materials sciences, spectral data
Year
2022
Journal
Frontiers in Molecular Biosciences
Volume
9
Pages
1 - 13
Document type
article
Publication state
published