Autophosphorylation of Rapeseed 2-Cys Peroxiredoxin

ARAN, M.; CAPORALETTI, D.; SENN, A.M.; TELLEZ DE IÑON, M.T.; GIROTTI, M.R.; LLERA, A.S.; WOLOSIUK, R.A.

Mar del Plata, Argentina.

Congreso; XLIII SAIB ANNUAL MEETING; 2007

Sociedad Argentina de Investigación en Bioquímica y Biología Molecular

2-Cys peroxiredoxins (2-Cys Prx) are widely distributed thiolcontaining peroxidases that have been implicated in various cellular processes. We have used functional and structural approaches to demonstrate that rapeseed 2-Cys Prx is a direct target for nucleotides. The concerted action of a nucleoside triphosphate and Mg impairs reversibly the peroxidase activity, being purine derivatives more efficient than pyrimidine counterparts. In particular, structural and site-directed mutagenesis studies are consistent with a mechanism where ATP interacts noncovalently with a region that contains the conserved Cys175. Most importantly, ATP triggers the autophosphorylation of 2-Cys Prx upon reduction with thiol-bearing compounds or phosphines followed by oxidation with hydroperoxides, quinones, tetrathionate, selenate or diamide. Mass spectrometry analysis reveals that 2-Cys Prx incorporates the phosphoryl moiety into the Cys175 residue yielding the sulfinic-phosphoryl [Prx-(Cys175)-SO2PO42-] and the sulfonic-phosphoryl [Prx-(Cys175)- SO3PO42-] anhydrides. Hence, the functional coupling betweenATP and 2-Cys Prx brings novel insights not only to the removal of toxic reactive oxygen species but also to mechanisms that link the status of cell energy to the oxidation of reactive cysteine residues.