Organization and regulatory mechanism of the promoters unique to photosynthesis nuclear genes

光合作用核基因特有启动子的组织与调控机制

基本信息

批准号：
14340253
负责人：
OBOKATA Junichi
金额：
$ 9.34万
依托单位：
Nagoya University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2002
资助国家：
日本
起止时间：
2002 至 2004
项目状态：
已结题

项目摘要

Core promoter is a region where preinitiation complex containing RNA polymerase II assembles, and located around the transcription start sites. In plant nuclear genes, core promoters generally contain TATA boxes as an essential element, and are believed to be indispensable for basal transcription but not involved in gene-specific regulation. However, we recently found the case where above assumption is not correct. The core promoter of a tobacco photosystem I gene, psaDb contains a pyrimidine-rich initiator element (Inr) but not a TATA box ; this core promoter architecture is referred to as a TATA-/Inr+ type. Experiments with various chimeric promoters revealed that the light-responsive transcription of psaDb effectively occurs only when the core promoter contains Inr, and TATA box cannot compensate for this Inr. This is the first example in plant genes that the core promoter architecture plays a pivotal role in gene-specific regulation. This finding raised a next question if this selective activation of the core promoter by upstream regulatory elements is unique to psaDb or common to a certain group of plant genes. In this study, we systematically analyzed the core promoter architecture of plant nuclear genes, and demonstrate that PSI genes constitute a unique group in respect to the architecture and function of their core promoters. The core promoters of the PSI gene group are generally TATA-/Inr+ or TATA-/Inr-types, and especially in the latter case, we found no promoter consensus motif so far identified in eukaryotic promoter systems. Swapping experiments of the upstream and core promoters between PSI genes and other TATA-containing plant genes revealed that core promoter requirement of PSI genes is quite different from that of the majority of plant nuclear genes.

核心启动子是一个含有RNA聚合酶II组装并位于转录起始位点的区域。在植物核基因中，核心启动子通常包含TATA盒作为必不可少的元素，并且认为对于基础转录是必不可少的，但不参与基因特异性调节。但是，我们最近发现上述假设不正确的情况。 PSADB是烟草光化系统I基因的核心启动子，其中包含一个富含嘧啶的引发剂元素（INR），但不包含tata盒。此核心启动子体系结构称为TATA-/INR+类型。使用各种嵌合启动子进行的实验表明，只有当核心启动子包含INR时，PSADB的光反应转录才有效发生，而TATA框无法补偿该INR。这是植物基因中的第一个例子，即核心启动子结构在基因特异性调节中起关键作用。如果上游调节元素对核心启动子的选择性激活是PSADB独有的或某些植物基因共有的，则这一发现提出了下一个问题。在这项研究中，我们系统地分析了植物核基因的核心启动子结构，并证明PSI基因构成了其核心启动子的结构和功能的独特群体。 PSI基因组的核心启动子通常是TATA-/INR+或TATA-/INR类型，尤其是在后一种情况下，我们发现在真核启动子系统中迄今未识别启动子共识基序。在PSI基因和其他含TATA的植物基因之间交换上游和核心启动子的实验表明，PSI基因的核心启动子需求与大多数植物核基因的需求完全不同。