High sensitivity of human centrin 2 toward radiolytical oxidation: C-terminal tyrosinyl residue as the main target.
Centrins are calcium-binding proteins that play a significant role in the maintenance of the centrosomal organization, mainly in the continuity between centrosome and microtubular network. Recent data showed that centrosome duplication abnormalities, like overduplication for example, could be due to hydrogen peroxide, suggesting an important impact of oxidative stress. To challenge this hypothesis, we performed one-electron oxidation experiments with human centrin 2, starting from azide radicals. Our results first revealed several intermolecular cross-links generating dimers, tetramers, hexamers, and higher molecular mass species. Dimers result from covalent bond linking the C-terminal tyrosines of each monomer. Second, the methionyl residue at position 19 was oxidized on the monomeric centrin. Further, electron microscopy experiments on centrin 2 showed a preexisting hexameric organization that was stabilized by covalent bonds as a result of irradiation. Overall, these results show that centrin 2 is highly sensitive to ionizing radiation, which could have important consequences on its biological functions.
Blouquit
Yves
Y
INSERM U759, Imagerie Intégrative, Campus Universitaire d'Orsay, Bât. 112, 91405 Orsay Cedex, France.
Duchambon
Patricia
P
Brun
Emilie
E
Marco
Sergio
S
Rusconi
Filippo
F
Sicard-Roselli
Cécile
C
D002118:Calcium / Q000494:pharmacology; D002135:Calcium-Binding Proteins / Q000737:chemistry / Q000235:genetics / Q000528:radiation effects* / Q000648:ultrastructure; D018929:Cell Culture Techniques / Q000379:methods; D018797:Cell Cycle Proteins / Q000737:chemistry / Q000235:genetics / Q000528:radiation effects* / Q000648:ultrastructure; D002942:Circular Dichroism; D003001:Cloning, Molecular; D014644:Genetic Variation; D006801:Humans; D008854:Microscopy, Electron; D010084:Oxidation-Reduction; D011994:Recombinant Proteins / Q000378:metabolism / Q000528:radiation effects; D014443:Tyrosine
C472752:CETN2 protein, human; D002135:Calcium-Binding Proteins; D018797:Cell Cycle Proteins; D011994:Recombinant Proteins; D014443:Tyrosine; D002118:Calcium