Synthesis and degradation of poly(ADP-ribose) in plants.

Poly(ADP-ribosylation) is a post-translational modification of proteins involved in a wide range of molecular and cellular processes in mammalian system. The main enzymes responsible for this modification are the poly(ADP-ribose) polymerases that catalyze the transfer of ADP-ribose moieties from NAD + to target protein acceptors, producing long and branched ADP-ribose polymers. The poly(ADP-ribosyl)ation is rapidly reverted by poly(ADP-ribose) glycohydrolase enzymes, which hydrolyzes poly(ADP-ribose) polymers, generating free ADP-ribose. So far, nine proteins with a poly(ADP-ribose) polymerase signature and two poly(ADP-ribose) glycohydrolase enzymes encoded by two adiacent genes were identified in Arabidopsis . The present review will describe the structures and functions of plant poly(ADP-ribose) polymerases and poly(ADP-ribose) glycohydrolases.