Ayadi Mira, Delaporte Virginie, Li You-Fang, Zhou Dao-Xiu
Faculté des Sciences, Université de Picardie Jules Verne, 33 rue Saint Leu, 80039 Amiens, France.
FEBS Lett. 2004 Mar 26;562(1-3):147-54. doi: 10.1016/S0014-5793(04)00222-4.
Trihelix DNA-binding factors (or GT factors) bind to GT elements found in the promoters of many plant genes. Although the binding specificity and the transcriptional activity of some members (e.g. GT-1 and GT-2) have been studied, the regulatory function of this family of transcription factors remains largely unknown. In this work, we have characterised a new GT factor, namely GT-3a, and a closely related member, GT-3b. We show that (1) they can form either homo- or heterodimers but do not interact with GT-1; (2) they are predominantly expressed in floral buds and roots; (3) GT-3a cannot bind to the binding sites of GT-1 or GT-2, but binds to the cab2 and rbcS-1A gene promoters via the 5'-GTTAC sequence, which has been previously shown to be the core of the Site 1 type of GT elements. These results suggest that GT-3a and GT-3b belong to a distinct subgroup of GT factors and that each subgroup of GT factors binds to a functionally distinct type of cis-acting GT elements.
三螺旋DNA结合因子（或GT因子）可与许多植物基因启动子中的GT元件结合。尽管已经对一些成员（如GT - 1和GT - 2）的结合特异性和转录活性进行了研究，但该转录因子家族的调控功能在很大程度上仍不清楚。在这项研究中，我们鉴定了一种新的GT因子，即GT - 3a，以及一个与之密切相关的成员GT - 3b。我们发现：（1）它们能形成同二聚体或异二聚体，但不与GT - 1相互作用；（2）它们主要在花芽和根中表达；（3）GT - 3a不能与GT - 1或GT - 2的结合位点结合，但能通过5'-GTTAC序列与cab2和rbcS - 1A基因启动子结合，该序列先前已被证明是GT元件1型位点的核心。这些结果表明，GT - 3a和GT - 3b属于GT因子的一个独特亚组，并且GT因子的每个亚组都与功能上不同类型的顺式作用GT元件结合。
