Smalle J, Kurepa J, Haegman M, Gielen J, Van Montagu M, Van Der Straeten D
Laboratorium voor Genetica, Departement Genetica, Vlaams Interuniversitair Instituut voor Biotechnologie, Universiteit Gent, K. L. Ledeganckstraat 35, B-9000 Gent, Belgium.
Proc Natl Acad Sci U S A. 1998 Mar 17;95(6):3318-22. doi: 10.1073/pnas.95.6.3318.
GT-2 is a plant transcriptional activator that contains two separate, but similar, trihelix DNA-binding domains. GT-1 is similar to GT-2, although it contains only one of such domains. cDNAs that encode GT-2 were isolated from rice (OS-GT2) and Arabidopsis (AT-GT2). Evidence is presented for the existence of an Arabidopsis gene family that is structurally related to AT-GT2. Two members of this GT2-like family, AT-GTL1 and AT-GTL2, have been isolated and characterized. Their sequences suggest that they evolved by a recent gene duplication event. Both AT-GT2 and AT-GTL genes contain an intron in the amino-terminal trihelix motif, indicating that this DNA-binding domain resulted from exon shuffling. RNA gel blot analysis using AT-GTL1 as a probe revealed four transcripts in the aerial part of the plant. All mRNA levels were significantly higher in siliques, suggesting that this gene family may function in fruit and/or seed development. To date, DNA-binding proteins characterized by the trihelix motif have been described only in plants, and may therefore be involved in plant-specific processes. Our results show that in Arabidopsis thaliana, the trihelix motif is not restricted to the GT-1 and GT-2 DNA-binding proteins.
GT-2是一种植物转录激活因子，它包含两个独立但相似的三螺旋DNA结合结构域。GT-1与GT-2相似，不过它只含有其中一个这样的结构域。从水稻（OS-GT2）和拟南芥（AT-GT2）中分离出了编码GT-2的cDNA。有证据表明存在一个与AT-GT2在结构上相关的拟南芥基因家族。这个GT2样家族的两个成员，AT-GTL1和AT-GTL2，已被分离并进行了表征。它们的序列表明它们是通过最近的基因复制事件进化而来的。AT-GT2和AT-GTL基因在氨基末端三螺旋基序中都含有一个内含子，这表明这个DNA结合结构域是由外显子重排产生的。以AT-GTL1为探针进行的RNA凝胶印迹分析揭示了植物地上部分有四种转录本。所有mRNA水平在角果中都显著更高，这表明这个基因家族可能在果实和/或种子发育中起作用。迄今为止，以三螺旋基序为特征的DNA结合蛋白仅在植物中被描述过，因此可能参与植物特有的过程。我们的结果表明，在拟南芥中，三螺旋基序并不局限于GT-1和GT-2 DNA结合蛋白。
