Abstract
ACC synthase (ACS) is a rate-limiting enzyme of ethylene biosynthesis pathway. We found that LeACS2, a wound-inducible ACS in tomato, was immediately phosphorylated after translation at Ser-460, and that half-life of phosphorylated LeACS2 was longer than non-phosphorylated LeACS2, suggesting that the turnover of LeACS2 protein in the cell is regulated by phosphorylation/dephosphorylation. Thus, we attempted to identify the protein phosphatase involved in LeACS2 turnover in this study. Biotin-tagged phosphorylated peptide (Biotinyl-454KNNLRL(pS)FSKRMYD467-CHO) was synthesized based on LeACS2 sequence. The 32 kDa protein which bound to the peptide was detected from the extract of wounded tomato fruit tissue and the amount of the protein was dependent on the peptide concentration, suggesting that the 32 kDa protein may a catalytic subunit of Ser/Thr protein phosphatase based on the molecular mass. We speculate the 32 kDa protein is involved in dephosphorylation of LeACS2 and try to identify the 32 kDa protein.
