熱誘導果蠅三磷酸鳥苷水解蛋白形成類澱粉蛋白特性之研究

果蠅三磷酸鳥苷蛋白，Beck，為表現在果蠅的腦部中蕈狀體的蛋白質，分子量22千道耳吞(22kDa)，胺基酸數量為185個。Beck是屬於 Rab (在腦部中發現與Ras相似蛋白)家族的蛋白質，且與之Rab同源蛋白有36%~78%的相似度，Rab 家族蛋白在生物體中專司於調節細胞的囊泡的形成，以及胞器間蛋白質的運輸。而Rab 家族也被報導發現與神經退化性疾病有關，例如: RAB7L1被報導與帕金森氏症相關缺陷疾病有關。本論文中，我們提出Beck 會因為溫度誘導使其由α- helice變成β-strand，並進一步形成類澱粉聚集。此現象我們經由會與amyloid專一性結合的染劑：硫代黄素-T及剛果紅和利用與蔗糖高速離心的方式，最後再用穿透式電子顯微鏡來確認Beck會形成類澱粉聚集。另外，Beck的非結合受質構型會形成較大的寡聚物，而結合受質構型為單體而穩定。本論文藉由研究Beck 蛋白質形成類澱粉聚集來探討該蛋白可能與神經退化性疾病有關。

關鍵字

三磷酸鳥苷水解蛋白；類澱粉蛋白

並列摘要

Drosophila melanogaster GTPase protein, Beck, was a 22kDa protein with 185 amino acids which was found in the mushroom of body brain. The Beck protein belongs to Rab family (Ras like protein in brain) and haves approximately 35%~78% sequence identities with other Rab family members. The Rab family proteins were reported to participate in cellular processes, such as facilitating vesicle formation and protein vesicle trafficking. Rab family protein were associated with neurodegenerative disease, for example, Parkinson’s disease-associated defects in Rab family protein, RAB7L1. In this study, we observed that Beck went through α-helical conformational to β-strand induced by thermal process and further form the amyloid-like β-aggregate which bind to specific dye, thioflavin-T and Congo red. The amyloid-like fibrils were centrifuged with sucrose and studied by using transmission electron microscopy. In addition, the free form of Beck shows protein aggregation and assembly into higher order, while GTP-bound form of Beck enhanced the correct folding and stability of monomer. Our studies of the Beck protein conformational change and formation of amyloid-like β-aggregate formation may contribute to the understanding of neurodegenerative diseases in Rab family proteins.

並列關鍵字

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參考文獻

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熱誘導果蠅三磷酸鳥苷水解蛋白形成類澱粉蛋白特性之研究

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