GT-1 BINDING-SITE CONFERS LIGHT RESPONSIVE EXPRESSION IN TRANSGENIC TOBACCO
GT-1 BINDING-SITE CONFERS LIGHT RESPONSIVE EXPRESSION IN TRANSGENIC TOBACCO
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DOI：
10.1126/science.2330508
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发表时间：
1990-04-27
期刊：
影响因子：
56.9
通讯作者：
CHUA, NH
中科院分区：
文献类型：
--
作者：
LAM, E;CHUA, NH
红细胞是编码核酮糖-1,5-二磷酸羧化酶小亚基的基因，是高等植物中参与碳固定的关键酶，其光依赖性表达在转录水平上受到调节。该基因的序列分析在许多红细胞启动子的-150至-100区域发现了一个保守的GT基序。这个基序是核因子GT-1的结合位点。对豌豆rbc-3A启动子位点特异性突变体的分析表明，GT-1在体外的结合与转基因植物中rbc启动子的光响应性表达相关。然而，目前尚不清楚除了GT-1以外的其他因子是否也需要光激活转录。一个合成的box II （TGTGTGGTTAATATG）四聚体（GT-1结合位点位于rbc-3A启动子-152至-138之间）插入截断的花菜花叶病毒35S启动子上游，足以在转基因烟草叶片中表达。这种表达主要发生在含叶绿体的细胞中，受光诱导，并与box II在体外结合GT-1的能力有关。数据显示GT-1的结合位点可能是红细胞激活的分子开关的一部分。
Light-dependent expression of rbcS, the gene encoding the small subunit of ribulose-1,5-bisphosphate carboxylase, which is the key enzyme involved in carbon fixation in higher plants, is regulated at the transcriptional level. Sequence analysis of the gene has uncovered a conserved GT motif in the -150 to -100 region of many rbcS promoters. This motif serves as the binding site of a nuclear factor, designated GT-1. Analysis of site-specific mutants of pea rbc-3A promotor demonstrated that GT-1 binding in vitro is correlated with light-responsive expression of the rbcS promoter in transgenic plants. However, it is not known whether factors other than GT-1 might also be required for activation of transcription by light. A synthetic tetramer of box II (TGTGTGGTTAATATG), the GT-1 binding site located between -152 to -138 of the rbc-3A promoter, inserted upstream of a truncated cauliflower mosaic virus 35S promoter is sufficient to confer expression in leaves of transgenic tobacco. This expression occurs principally in chloroplast-containing cells, is induced by light, and is correlated with the ability of box II to bind GT-1 in vitro. The data show that the binding site for GT-1 is likely to be a part of the molecular light switch for rbcS activation.