Abstract
Acylamino acid-releasing enzyme (AARE) catalyzes the N-terminal hydrolysis ofN-acylpeptides to release N-acylated amino acid. In the genome sequence from Arabidopsis thaliana,a gene that was homologous to the mammalian gene for AARE was found by BLAST search. The gene was amplified by RT-PCR and subcloned into an expression vector, pQE32. Cloned cDNA coded 694 amino acids, and this amino acid sequence showed 28% identity with those of AAREs from mammalians. Especially, the proposed active residues (Ser, Asp, and His) of AARE, called "catalytic triad residues" were completely conserved. Overexpressed AARE protein in E.coli protein showed AARE activity, and it was similar to those of native AARE prepared from cucumber and Arabidopsis leaves. Furthermore, native AARE degraded glycated riblose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) but not native Rubisco. These results indicate that plants have AARE, and plant AARE might have roles in elimination of glycated proteins as well as mammalian AAREs.
