ATP modulates peroxidase activity and elicits autophosphorylation of rapeseed 2-Cys Peroxiredoxin

ARAN, M.; CAPORALETTI, D.; SENN, A.; ETCHEGOYEN, J.I.; TELLEZ DE IÑON, M.T.; WOLOSIUK, R.A.

Rosario, Argentina.

Congreso; XLII SAIB ANNUAL MEETING; 2006

Sociedad Argentina de Investigación en Bioquímica y Biología Molecular

2-Cys peroxiredoxins (2-Cys Prx) are ubiquitous peroxidases devoid of selenium- and the heme-prosthetic group that have been implicated in cell proliferation, differentiation, apoptosis, and photosynthesis. Although the contribution to the cell redox status has been characterized and the chaperone capacity was recently reported, the precise control of functional characteristics remains unknown. We found that ATP impairs reversibly the peroxidase activity associated to chloroplast rapeseed 2-Cys Prx. In particular, the noncovalent interaction with ATP not only modifies the catalytic activity but also changes the structural features of the recombinant protein. More importantly, ATP triggers the autophosphorylation of the chloroplast 2-Cys Prx when the protein is successively treated with a reductant and an oxidant. Contrary to the peroxidatic activity, the conserved Cys175 and Trp179 residues are essential for the incorporation of radioactivity from [γ-32P]ATP. Despite significant differences, the process of autophosphorylation is also observed with orthologs from a helminth parasite (Schistosoma mansoni 2-Cys Prx1) and bacteria (Salmonella typhimurium AhpC). These results uncover a previously unknown function of ATP in the regulation of 2-Cys Prx and give a new insight not only to the removal of obnoxious reactive oxygen species but also to the control of signal transduction pathways.