Molecular characterization of regulatory genes for nicotine biosynthesis in tobacco

转录因子（TF）识别具有不同DNA结合结构域（DBD）的靶DNA序列。拟南芥（Arabidopsis thaliana）乙烯应答因子1（AtERF 1）的DBD使用三个连续的β链来识别含有GCC的序列，但烟草（Nicotiana tabacum）ERF 189和长春花（Catharanthus roseus）十八烷衍生物响应性Catharanthus AP 2结构域蛋白3（ORCA 3）的TF亚组似乎靶向相似但不同的DNA序列。在这里，我们研究了这些TF的DNA结合特异性如何在每个植物谱系中分化，以调节不同的防御代谢。这些DBD的广泛的突变分析表明，蛋白质-DNA相互作用的两种模式独立地有助于结合特异性和亲和力的ERF的DNA结合特异性的差异可能已经出现通过这些氨基酸残基的突变变化。

Transcription factors (TFs) recognize target DNA sequences with distinct DNA-binding domains (DBDs). The DBD of Arabidopsis (Arabidopsis thaliana) ETHYLENE RESPONSE FACTOR1 (AtERF1) uses three consecutive beta-strands to recognize a GCC-containing sequence, but tobacco (Nicotiana tabacum) ERF189 and periwinkle (Catharanthus roseus) Octadecanoid-derivative Responsive Catharanthus AP2-domain protein3 (ORCA3) of the same TF subgroup appear to target similar but divergent DNA sequences. Here, we examined how DNA-binding specificities of these TFs have diverged in each plant lineage to regulate distinct defense metabolisms. Extensive mutational analyses of these DBDs suggest that two modes of protein-DNA interactions independently contribute to binding specificity and affinity Divergent DNA-binding specificities of the ERFs may have arisen through mutational changes of these amino acid residues.