Processing of Mammalian and PlantS-Adenosylmethionine Decarboxylase Proenzymes

摘要: Abstract S-Adenosylmethionine decarboxylase (AdoMetDC) is a pyruvoyl enzyme, and the pyruvate formed in an intramolecular reaction that cleaves proenzyme precursor converts serine residue into pyruvate. The wild type potato AdoMetDC processed much faster than human did not require putrescine for optimal rate of processing despite presence three acidic residues (equivalent to Glu11, Glu178, Glu256) were demonstrated previous studies be required activation (Stanley, B. A., Shantz, L. M., Pegg, A. E. (1994) J. Biol. Chem. 269, 7901–7907). A fourth also needed stimulation was identified present studies, this (Asp174) sequence. site found Ser73 conserved sequence, YVLSESS, which equivalent Ser68 Replacement with threonine or cysteine by site-directed mutagenesis either prevent but caused significant reduction rate. Although COOH-terminal regions known eukaryotic AdoMetDCs are conserved, only relatively small truncations 8 from protein 25 compatible processing. maximally truncated proteins show no similarity amino acid sequence each contained 46 after last suggesting length section essential maintaining conformation autocatalytic