influence of ATP on the binding of zebrafish(Danio rerio)vitellogenin1-like proteins to UV-damaged DNA and the action mechanism

• Main Authors: Hui-Ying Huang, 黃惠英
• Other Authors: Chin-Hwa Hu
• Format: Others
• Language: zh-TW
• Published: 2007
• Online Access: http://ndltd.ncl.edu.tw/handle/00805333113191883959

碩士 === 國立臺灣海洋大學 === 生物科技研究所 === 95 === Abstract In most organisms, cyclobutane pyrimidine dimmers (CPDs) and (6-4) photoproducts (6-4 PPs) produced after UV irradiation are removed from damaged DNA primarily by nucleotide excision repair (NER) that introduces a dual incision at both ends of the lesion after an ATP-dependent DNA zebrafish (Danio rerio) vitellogenin 1 (zfVg1) had been identified as the components of a UV-damaged-DNA binding activity highly expressed in zebrafish embryos at 12 hr post fertilization (hpf) (Lai et al., 2006). Because of the requirement of ATP for DNA unwinding during NER, the effects of ATP on the binding of zfVg1-like proteins to 6-4PPs were examined in this study. The binding of 12 hpf zebrafish extract proteins to a 6-4 PP probe was suppressed by 2mM ATP and partially inhibited by ATP-γ-S at the same concentration. Hence, 6-4PP-dependent binding suppressed by ATP was mediated through ATP hydrolysis. The pH change induced by ATP addition was unable to produce the suppressive effect. The inability of ATP-treated extracts to bind 6-4PPs correlated well with the disappearance of a few 70 to 100-kDa zfVg1-like polypeptides electrofocused at pH about 3.5 and the appearance of novel 33 to 90-kDa zfVg1-like factors having neutral to weak basic pIs, indicating the importance of high-molecular-weight zfVg1-like factors in maintaining the UV-binding activity except the two 30 to 35 kDa polypeptides. High and low-molecular-weight zfVg1-like proteins contained in zebrafish extracts might contact UV-damaged DNA as protein complexes after immunoblot analysis of UV-binding protein fractions. ATP was found to disturb UV-dependent binding via protein phosphorylation induced 1 min after ATP addition. The physiological role of this ATP-induced suppression of UV-dependent binding awaits further investigation.