| Summary: | 碩士 === 國立陽明大學 === 生命科學系暨基因體科學研究所 === 105 === Eukaryotes evolved a specific strategy for DNA packaging. A repeating unit, nucleosome, consists of 147 base pairs of DNA segment wrapped histone core proteins. Nucleosome plays an important role in the regulation of DNA-dependent biosynthesis and gene expression by its structure. Chromatin structure remodeling complex (RSC, Remodel the Structure of Chromatin) is essential for the regulation of nucleosome structure in vivo. Previous researches indicated that RSC complex can hydrolyze ATP to perturb nucleosome structures resulting in nucleosome sliding and histone octamer ejection. However, the mechanisms and the transition state of RSC-mediated nucleosome remodeling are still unclear. Here we utilize tether particle motion (TPM) experiments to investigate the RSC-mediated nucleosome remodeling process in detail. RSC has been known to play an important role in DNA-dependent biosynthesis pathways. Therefore, we study the interplay between RSC and other factors, acceptor DNA and nucleosome assembly protein (Nap1). By using TPM experiments, the histone octamer ejection was observed during RSC-mediated nucleosome remodeling. Moreover, the high percentage of the RSC-mediated histone octamer ejection was observed under saturated ATP and in the presence of acceptor DNA. In contrast, the ratio of RSC-mediated histone octamer ejection decreased in the presence of Nap1. In this project, the whole reaction scheme of RSC-mediated nucleosome remodeling process, including nucleosome sliding and histone octamer ejection, can be depicted based on TPM results.
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