Biastoff Stefan, Reinhardt Nicole, Reva Veaceslav, Brandt Wolfgang, Dräger Birgit
Institute of Pharmacy, Faculty of Science I, Martin Luther University Halle-Wittenberg, Hoher Weg 8, D-06120 Halle, Germany.
FEBS Lett. 2009 Oct 20;583(20):3367-74. doi: 10.1016/j.febslet.2009.09.043. Epub 2009 Sep 29.
Putrescine N-methyltransferase (PMT) catalyses S-adenosylmethionine (SAM)-dependent methylation of putrescine in tropane alkaloid biosynthesis. PMT presumably evolved from the ubiquitous spermidine synthase (SPDS). SPDS protein structure suggested that only few amino acid exchanges in the active site were necessary to achieve PMT activity. Protein modelling, mutagenesis, and chimeric protein construction were applied to trace back evolution of PMT activity from SPDS. Ten amino acid exchanges in Datura stramonium SPDS dismissed the hypothesis of facile generation of PMT activity in existing SPDS proteins. Chimeric PMT and SPDS enzymes were active and indicated the necessity for a different putrescine binding site when PMT developed.
腐胺N-甲基转移酶（PMT）在托烷生物碱生物合成中催化腐胺的S-腺苷甲硫氨酸（SAM）依赖性甲基化。PMT可能由普遍存在的亚精胺合酶（SPDS）进化而来。SPDS的蛋白质结构表明，活性位点只需少数氨基酸交换就能实现PMT活性。通过蛋白质建模、诱变和嵌合蛋白构建来追溯PMT活性从SPDS的进化过程。曼陀罗SPDS中的十个氨基酸交换否定了现有SPDS蛋白中能轻易产生PMT活性的假说。嵌合PMT和SPDS酶具有活性，表明PMT产生时需要一个不同的腐胺结合位点。
