Hashimoto T, Tamaki K, Suzuki K, Yamada Y
Graduate School of Biological Sciences, Nara Institute of Science and Technology, Japan.
Plant Cell Physiol. 1998 Jan;39(1):73-9. doi: 10.1093/oxfordjournals.pcp.a029291.
Four cDNAs for spermidine synthase (SPDS), which converts the diamine putrescine to the higher polyamine spermidine using decarboxylated S-adenosylmethionine as the co-factor, were isolated from Nicotiana sylvestris, Hyoscyamus niger, and Arabidopsis thaliana. When the N.sylvestris SPDS cDNA was expressed in a SPDS-deficient E. coli mutant, the recombinant protein showed high SPDS activity, but did not have any spermine synthase activity. The plant SPDSs have molecular masses of about 34 kDa, possess the co-factor binding motifs which have been proposed for S-adenosylmethionine, and are more homologous in amino acid sequence to tobacco putrescine N-methyltransferase (PMT) than to SPDSs from mammals and E. coli. The SPDS gene is expressed in root, stem, and leaf in N.sylvestris, whereas the PMT gene is expressed only in root. The potential evolution of plant SPDS and PMT, and their evolutionary relationships with animal SPDS are discussed.
从野生烟草、黑种草和拟南芥中分离出了4个亚精胺合酶（SPDS）的cDNA，该酶以脱羧的S-腺苷甲硫氨酸作为辅因子，将二胺腐胺转化为高级多胺亚精胺。当野生烟草SPDS cDNA在缺乏SPDS的大肠杆菌突变体中表达时，重组蛋白表现出较高的SPDS活性，但没有任何精胺合酶活性。植物SPDS的分子量约为34 kDa，具有已被提出用于S-腺苷甲硫氨酸的辅因子结合基序，并且在氨基酸序列上与烟草腐胺N-甲基转移酶（PMT）的同源性高于与哺乳动物和大肠杆菌的SPDS的同源性。SPDS基因在野生烟草的根、茎和叶中表达，而PMT基因仅在根中表达。文中讨论了植物SPDS和PMT的潜在进化以及它们与动物SPDS的进化关系。
