| Summary: | 碩士 === 國立臺灣師範大學 === 生命科學研究所 === 97 === Chloroplast, originated from endosymbiotic cyanobacteria in the ancient times, is one of the most important organelles in plants for it’s function of photosynthesis. During the evolution of plant cells, more than ninety percent of the plastid genes were gradually transferred to the host nuclear genome. However, these genes have to be transcribed in nucleus, translated and post-translationally modified in cytoplasm, and imported to plastids accurately. The translocons on the outer envelope and inner envelope membrane of chloroplast play key roles on machinery of protein import into the chloroplast. They compose two complexes: Toc complex (Translocon at the Outer envelope membrane of the Chloroplast) and Tic complex (Translocon at the Inner envelope membrane of the Chloroplast). Among the Toc and Tic components identified in Arabidopsis thaliana, atToc33 and atToc34 are homologous to pea psToc34 and play important roles of pre-protein recognition. Evidently, the expression of translocon genes have to be regulated properly, or their gene products will not be accurately integrated to their destination and proceed their mission. In order to reveal the regulatory mechanism of atToc33 and atToc34 gene expression, transgenes containing the promoter sequences of atToc33 and atToc34 gene and GUS coding sequence were transferred into wild-type Arabidopsis. The 1st intron in the 5’UTR of both gene have obvious effect on the regulation of gene expression. Furthermore, 5’ promoter deletion and EMSA experiments reveal several putative regulation regions of promoter sequence to modulate atToc33 expression.
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