RF2b, a rice bZIP transcription activator, interacts with RF2a and is involved in symptom development of rice tungro disease
RF2b, a rice bZIP transcription activator, interacts with RF2a and is involved in symptom development of rice tungro disease
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DOI：
10.1073/pnas.0307687100
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发表时间：
2004-01-13
影响因子：
11.1
通讯作者：
Beachy, RN
中科院分区：
文献类型：
--
作者：
Dai, SH;Zhang, ZH;Beachy, RN
水稻东格鲁杆状病毒（RTBV）的韧皮部特异性启动子部分受序列特异性DNA结合蛋白的调控，这些蛋白与Box II（一个必需的顺式元件）结合。先前的研究表明，bZIP蛋白RF 2a参与RTBV启动子的转录调控。在这里，我们报告的第二个蛋白质，RF 2b的识别和功能特性。通过其与RF 2a的相互作用鉴定的RF 2b在体外测定中作为同源二聚体和RF 2a/RF 2b异源二聚体与盒II结合。与RF 2a一样，RF 2b在瞬时测定和转基因烟草植物中激活RTBV启动子。Ma和RF 2b都主要在血管组织中表达。然而，RF 2a和RF 2b具有不同的DNA结合亲和力框II，在不同的水稻器官中表现出独特的表达模式，并表现出不同的亚细胞定位模式。此外，具有降低水平的RF 2b的转基因水稻植物表现出疾病样表型。我们建议，调控韧皮部特异性表达的RTBV启动子和潜在的RTBV复制的控制主要是通过盒II顺式元件与多种宿主因子，包括马和RF 2b的相互作用来实现的。我们还建议，淬火/滴定这些和其他转录因子RTBV参与水稻东格鲁病的症状的发展。
The phloem-specific promoter of rice tungro bacilliform virus (RTBV) is regulated in part by sequence-specific DNA-binding proteins that bind to Box II, an essential cis element. Previous studies demonstrated that the bZIP protein RF2a is involved in transcriptional regulation of the RTBV promoter. Here we report the identification and functional characterization of a second protein, RF2b. RF2b, identified by its interaction with RF2a, binds to Box II in in vitro assays as a homodimer and as RF2a/RF2b heterodimers. Like RF2a, RF2b activates the RTBV promoter in transient assays and in transgenic tobacco plants. Both Ma and RF2b are predominantly expressed in vascular tissues. However, RF2a and RF2b have different DNA-binding affinities to Box II, show distinctive expression patterns in different rice organs, and exhibit different patterns of subcellular localization. Furthermore, transgenic rice plants with reduced levels of RF2b exhibit a disease-like phenotype. We propose that the regulation of phloem-specific expression of the RTBV promoter and potentially the control of RTBV replication are mainly achieved via interactions of the Box II cis element with multiple host factors, including Ma and RF2b. We also propose that quenching/titration of these and perhaps other transcription factors by RTBV is involved in the development of the symptoms of rice tungro disease.