Meijer A H, Scarpella E, van Dijk E L, Qin L, Taal A J, Rueb S, Harrington S E, McCouch S R, Schilperoort R A, Hoge J H
Institute of Molecular Plant Sciences, Leiden University, Clusius Laboratory, The Netherlands.
Plant J. 1997 Feb;11(2):263-76. doi: 10.1046/j.1365-313x.1997.11020263.x.
This paper describes the characterization of Oshox1, a cDNA clone from rice encoding a member of the homeodomain-leucine zipper (HD-Zip) class of putative transcription factors. Oshox1 maps to chromosome 10 and belongs to a family of related rice genes. Two-hybrid assays showed that Oshox1 protein can homodimerize, but can also form heterodimers with an Arabidopsis HD-Zip protein. This suggests that protein-protein interactions may also occur between different HD-Zip proteins in rice, which would provide enormous versatility for generating specific gene-control mechanisms. Oshox1 mRNA could be detected in various rice tissues at different developmental stages, with highest levels in embryos, shoots of seedlings, and leaves of mature plants. Transgenic expression of Oshox1 in Arabidopsis retarded growth and affected leaf size and shape, indicative of a role as developmental regulator. In vitro and in vivo DNA-binding studies revealed that Oshox1 interacts with the pseudopalindromic sequence CAAT(C/G)ATTG, confirming that the protein represents a transcription factor. Oshox1 was found to repress reporter gene activity in rice suspension cells, most likely by a mechanism of active transcriptional repression. Repression was strictly dependent on the presence of upstream Oshox1 binding sites in the reporter gene constructs and a function of the N-terminal region of Oshox1, preceding the homeodomain.
本文描述了Oshox1的特性，它是一个来自水稻的cDNA克隆，编码一个属于假定转录因子同源域-亮氨酸拉链（HD-Zip）类别的成员。Oshox1定位于第10号染色体，属于一个相关水稻基因家族。双杂交分析表明，Oshox1蛋白可以同二聚化，但也能与拟南芥HD-Zip蛋白形成异二聚体。这表明水稻中不同的HD-Zip蛋白之间也可能发生蛋白质-蛋白质相互作用，这将为产生特定的基因控制机制提供巨大的通用性。在不同发育阶段的各种水稻组织中都能检测到Oshox1 mRNA，在胚、幼苗的芽和成熟植株的叶中含量最高。Oshox1在拟南芥中的转基因表达延迟了生长，并影响了叶片大小和形状，表明其作为发育调节因子的作用。体外和体内DNA结合研究表明，Oshox1与假回文序列CAAT(C/G)ATTG相互作用，证实该蛋白代表一种转录因子。发现Oshox1在水稻悬浮细胞中抑制报告基因活性，最有可能是通过一种主动转录抑制机制。抑制作用严格依赖于报告基因构建体中上游Oshox1结合位点的存在以及Oshox1在同源域之前的N端区域的功能。
