Oxidative stress induces mainly human centrin 2 polymerisation.
OBJECTIVE
To determine the human centrin 2 (Hscen 2) protein response to oxidising radicals in vitro and to evaluate the consequences on its biological functions.


METHODS
Hscen 2 was submitted to hydroxyl and azide radicals produced by radiolysis in the absence of oxygen. The resulting products were characterised by biochemical, spectroscopic and mass spectrometry techniques. Their thermodynamics parameters of complexation with C-terminal fragment of Xeroderma pigmentosum C protein (C-XPC), one of the Hscen 2 cellular partners, were quantified by isothermal titration calorimetry (ITC).


RESULTS
Both hydroxyl and azide radicals induce centrin 2 polymerisation as we characterised several intermolecular cross-links generating dimers, trimers, tetramers and higher molecular mass species. These cross-links result from the formation of a covalent bond between the only tyrosine residue (Tyr 172) located in the C-terminal region of each monomer. Remarkably, dimerisation occurs for doses as low as a few grays. Moreover, this Hscen2 dimer has a lower affinity and stoechiometry binding to C-XPC.


CONCLUSIONS
These results show that as oxidative radicals induce high proportions of irreversible damages (polymerisation) centrin 2 is highly sensitive to ionising radiation. This could have important consequences on its biological functions.
Brun
Emilie
E
Laboratoire de Chimie Physique, CNRS UMR 8000, Université Paris-Sud 11, Bât. 350, Orsay Cedex, France.
Blouquit
Yves
Y
Duchambon
Patricia
P
Malosse
Christian
C
Chamot-Rooke
Julia
J
Sicard-Roselli
Cécile
C
D002135:Calcium-Binding Proteins / Q000737:chemistry* / Q000528:radiation effects; D002151:Calorimetry; D018797:Cell Cycle Proteins / Q000737:chemistry* / Q000528:radiation effects; D002942:Circular Dichroism; D004268:DNA-Binding Proteins / Q000737:chemistry; D005609:Free Radicals; D006801:Humans; D013058:Mass Spectrometry; D018384:Oxidative Stress; D055503:Protein Multimerization; D013056:Spectrophotometry, Ultraviolet; D013816:Thermodynamics
C472752:CETN2 protein, human; D002135:Calcium-Binding Proteins; D018797:Cell Cycle Proteins; D004268:DNA-Binding Proteins; D005609:Free Radicals; C086984:XPC protein, human