Suzuki K, Yamada Y, Hashimoto T
Graduate School of Biological Sciences, Nara Institute of Science and Technology, Japan.
Plant Cell Physiol. 1999 Mar;40(3):289-97. doi: 10.1093/oxfordjournals.pcp.a029540.
The cDNAs encoding putrescine N-methyltransferase (PMT), which catalyzes the S-adenosylmethionine-dependent N-methylation of putrescine at the first committed step in the biosynthetic pathways of tropane alkaloids, were isolated from Atropa belladonna and Hyoscyamus niger. These PMTs, however, lacked the N-terminal tandem repeat arrays previously found in Nicotiana PMTs. AbPMT1 RNA was much more abundant in the root of A. belladonna than was AbPMT2 RNA. The 5'-flanking region of the AbPMT1 gene was fused to the beta-glucuronidase (GUS) reporter gene and transferred to A. belladonna. Histochemical analysis showed that GUS is expressed specifically in root pericycle cells and that the 0.3-kb 5'-upstream region was sufficient for pericycle-specific expression. Treatment of A. belladonna roots with methyl jasmonate did not up-regulate the expression of GUS or endogenous AbPMT genes. The regulation of tropane alkaloid biosynthesis is discussed and compared with that of nicotine biosynthesis.
编码腐胺N-甲基转移酶（PMT）的cDNA从颠茄和黑种草中分离得到，该酶在托烷生物碱生物合成途径的第一个关键步骤催化依赖于S-腺苷甲硫氨酸的腐胺N-甲基化反应。然而，这些PMT缺乏先前在烟草PMT中发现的N端串联重复序列。AbPMT1 RNA在颠茄根中的丰度比AbPMT2 RNA高得多。将AbPMT1基因的5'侧翼区与β-葡萄糖醛酸酶（GUS）报告基因融合，并导入颠茄。组织化学分析表明，GUS在根中柱鞘细胞中特异性表达，0.3 kb的5'上游区域足以实现中柱鞘特异性表达。用茉莉酸甲酯处理颠茄根并没有上调GUS或内源性AbPMT基因的表达。本文对托烷生物碱生物合成的调控进行了讨论，并与尼古丁生物合成的调控进行了比较。
