Selenocysteine robustness versus cysteine versatility: a hypothesis on the evolution of the moonlighting behaviour of peroxiredoxins.
Peroxiredoxins (Prxs) and glutathione peroxidases (Gpxs) provide the majority of peroxides reducing activity in the cytoplasm. Both are peroxidases but differences in the chemical mechanism of reduction of oxidative agents, as well as in the reactivity of the catalytically active residues, confer peculiar features on them. Ultimately, Gpx should be regarded as an efficient peroxides scavenger having a high-reactive selenocysteine (Sec) residue. Prx, by having a low pKa cysteine, is less efficient than Gpx in reduction of peroxides under physiological conditions, but the chemistry of the sulfur together with the peculiar structural arrangement of the active site, in typical Prxs, make it suitable to sense a redox environment and to switch-in-function so as to exert holdase activity under redox-stress conditions. The complex macromolecular assembly would have evolved the chaperone holdase function and the moonlighting behaviour typical of many Prxs.
*Istituto Pasteur-Fondazione Cenci-Bolognetti and Dipartimento di Scienze Biochimiche "A. Rossi Fanelli", Sapienza Università di Roma, Piazzale A. Moro 5, 00185 Rome, Italy.
Fulvio
F
Saccoccia
†Dipartimento di Medicina clinica, sanità pubblica, scienze della vita e dell'ambiente, Piazzale Salvatore Tommasi 1, 67100 L'Aquila, Italy.
Francesco
F
Angelucci
*Istituto Pasteur-Fondazione Cenci-Bolognetti and Dipartimento di Scienze Biochimiche "A. Rossi Fanelli", Sapienza Università di Roma, Piazzale A. Moro 5, 00185 Rome, Italy.
Giovanna
G
Boumis
*Istituto Pasteur-Fondazione Cenci-Bolognetti and Dipartimento di Scienze Biochimiche "A. Rossi Fanelli", Sapienza Università di Roma, Piazzale A. Moro 5, 00185 Rome, Italy.
Gianni
G
Desiato
*Istituto Pasteur-Fondazione Cenci-Bolognetti and Dipartimento di Scienze Biochimiche "A. Rossi Fanelli", Sapienza Università di Roma, Piazzale A. Moro 5, 00185 Rome, Italy.
Adriana E
AE
Miele
Andrea
A
Bellelli
D055162:Biocatalysis; D005075:Biological Evolution; D003545:Cysteine / Q000378:metabolism*; D008958:Models, Molecular; D010084:Oxidation-Reduction; D054464:Peroxiredoxins / Q000737:chemistry / Q000502:physiology*; D011487:Protein Conformation; D017279:Selenocysteine / Q000378:metabolism*
D017279:Selenocysteine; D054464:Peroxiredoxins; D003545:Cysteine