Diversity and functional differentiation of preinitiation complex of transcription in plants

点击翻译按钮获取中文摘要

Core promoter is a region where preinitiation complex containing RNA polymerase II assembles, and located around the transcription start sites. However, the majority of plant promoters do not have any recognizable core promoter elements, which reflects our limited understanding of plant promoters.We hut:la fed this grant project by elucidating the core promoter architecture of the plant genome. For this sake, we took the combined approach of in silico detection of novel core promoter elements and large-scale determination of transcription start sites (TSSs). We developed a novel methodology for TSS identification, using a combination of the Cap-Trapper and Massively Parallel Signature Sequencing methods. This technique, CT-MPSS, allowed us to identify 158,237 Arabidopsis TSS tags corresponding to 38,311 TSS loci, which has provided an opportunity for quantitative analysis of plant promoters for the first time. The expression characteristics of these core promoters were analyzed in resp … More ect to core promoter elements detected. by our in silico analyses, revealing that Arabidopsis promoters contain two major types with exclusive characteristics, a TATA type and a GA type. The TATA-type promoters tend to be associated with the Y Patch and Inr, and cause high-level expression with TSS clusters of sharp peak. By contrast, the GA type produces broad-type TSS clusters. Unlike mammalian promoters, plant promoters are not associated with CpG islands. However, plant-specific GA-type promoters share some characteristics with mammalian CpG-type promotersNext, we examined the functional differentiation of core promoter elements with respect to tissue-specific and light-responsive transcriptional regulation, using Arabidopsis photosynthesis genes as a model case. We made a series of swapping constructs of regulatory and core promoter segments from various genes, and their reporter fusions were introduced into plants. Analysis of the expression characteristics of these chimeric promoter constructs revealed that upstream regulatory elements each have preference to specific type of core promoter subtypes. This finding implies that the functional differentiation of core promoter subtypes may reflect the functional differentiation of transcriptional preinitiation complexes. Less