Johannesson H, Wang Y, Engström P
Department of Evolutionary Biology, Physiological Botany, Uppsala, Sweden.
Plant Mol Biol. 2001 Jan;45(1):63-73. doi: 10.1023/a:1006423324025.
Homeodomain-leucine zipper (HDZip) proteins constitute a large family of transcription factors apparently unique to plants. In this report we characterize the DNA-binding and dimerization preferences in vitro of class I HDZip proteins. Using gel-exclusion chromatography and in vitro protein binding assays we demonstrate that the HDZip class I protein ATHB5 forms a homodimeric complex in solution. Consistent with this finding we have demonstrated the sequence-specific interaction of ATHB5 with a 9 bp pseudopalindromic DNA sequence, CAATNATTG, composed of two half-sites overlapping at a central position, by use of a PCR-assisted binding-site selection assay and competitive EMSA experiments. A majority of other known members of HDZip class I interacted with similar DNA sequences, but differed in their preference for A/T versus G/C in the central position of the binding site. Selective heterodimerization in vitro was demonstrated between ATHB5 and different class I HDZip proteins. Heterodimer formation between class I HDZip proteins is of potential functional significance for the integration of information from different signalling pathways in the control of plant development.
同源异型域-亮氨酸拉链（HDZip）蛋白构成了一个显然为植物所特有的转录因子大家族。在本报告中，我们对I类HDZip蛋白在体外的DNA结合和二聚化偏好进行了表征。使用凝胶排阻色谱法和体外蛋白结合试验，我们证明I类HDZip蛋白ATHB5在溶液中形成同源二聚体复合物。与此发现一致，我们通过PCR辅助的结合位点选择试验和竞争性电泳迁移率变动分析实验，证明了ATHB5与一个由两个在中心位置重叠的半位点组成的9碱基对假回文DNA序列CAATNATTG的序列特异性相互作用。I类HDZip的大多数其他已知成员与相似的DNA序列相互作用，但在结合位点中心位置对A/T与G/C的偏好有所不同。我们在体外证明了ATHB5与不同的I类HDZip蛋白之间的选择性异源二聚化。I类HDZip蛋白之间的异源二聚体形成对于在植物发育控制中整合来自不同信号通路的信息具有潜在的功能意义。
