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Title: | EB病毒的BSLF1蛋白質對於外鞘蛋白質的影響 Effects of BSLF1 on capsid proteins of Epstein-Barr virus |
Authors: | Hsiao-Chein Huang 黃筱茜 |
Advisor: | 張麗冠 |
Keyword: | EB病毒,BSLF1,去泛素化,deubiquitinase,外鞘蛋白質,BFRF3,BORF1, Epstein-Barr Virus (EBV),BSLF1,deubiquitinase (DUB),capsid proteins,BFRF3,BORF1, |
Publication Year : | 2014 |
Degree: | 碩士 |
Abstract: | Epstein-Barr virus (EB病毒) 屬於人類皰疹病毒科,與上皮細胞及淋巴的惡性腫瘤與鼻咽癌有密切關係,其生活史包含了潛伏期和溶裂期,病毒感染細胞後以潛伏期的情況在細胞中,當受到特定因子刺激後,會誘導病毒進入溶裂循環。在溶裂循環時期,病毒會開始複製其遺傳物質及病毒蛋白質,而病毒蛋白質依照表現的先後順序可以分為極早期蛋白質、早期蛋白質及晚期蛋白質,並且透過這些蛋白質包裹遺傳物質,組裝形成病毒顆粒。泛素化修飾在病毒的複製及感染中扮演重要的角色,而許多的病毒蛋白質都可以被泛素修飾,甚至是身為泛素化修飾中酵素的一員,而本篇研究中的BSLF1為EB病毒的複製蛋白質且已被報導具有去泛素化 (deubiquitinase, DUB) 的活性。本研究利用純化出的BSLF1抗體,發現細胞被誘導進入溶裂期後十二到四十八小時BSLF1都有表現,並以免疫螢光染色觀察其在細胞中的分佈。接著利用In vitro DUB assay確認BSLF1具有去泛素化的活性。然後以共免疫沉澱分析發現BSLF1會與EB病毒的外鞘蛋白BFRF3及BORF1有交互作用,並且以GST pulldown assay發現BSLF1與BFRF3有直接的交互作用,且可以讓BFRF3的蛋白質較穩定,顯示BSLF1可以將BFRF3去泛素化,不會被送到proteasome降解。最後,設計了一系列的BSLF1截切突變株,發現所有突變株都可以與BFRF3結合,但只有BSLF1-N710還具有去泛素化的活性,而N540及N640則否,因此推論BSLF1的第640到710胺基酸對於去泛素活性是重要的。以上結果顯示,具有去泛素化活性的BSLF1可以藉由與外鞘蛋白BFRF3的交互作用,使得BFRF3被去泛素化而趨於穩定,因為外鞘蛋白質的穩定性提高,可能使得EB病毒顆粒釋出的量也隨之增加。 Epstein-Barr virus (EBV) is a human herpesvirus that infects up to 90% population and causes malignancies such as Burkitt’s lymphoma, nasopharyngeal carcinoma, and lymphoproliferative diseases. This virus contains two distinct life cycles, and is usually maintained under latent conditions after infection, and turns to the lytic phase after lytic induction. During the lytic phase, the virus encodes immediate-early, early, and late genes to produce virus particles. BSLF1 encodes a primase, which is required for lytic DNA replication. Previous study showed that BSLF1 contains deubiquitinase (DUB) activity. In this study, we aim to find the effects of BSLF1 on capsid proteins of EBV. This study finds that BSLF1 is expressed at 24 hrs after lytic induction. In vitro DUB assay revealed that BSLF1 contains DUB activity. Moreover, immunoprecipitation indicated that BSLF1 interacts with two EBV capsid proteins, BFRF3 and BORF1. Futhermore, GST pulldown assay shows that BSLF1 interacts with BFRF3 directly. BSLF1 overexpression reduces the levels of ubiquitinated BFRF3 and BORF1, thereby increasing the stability of BFRF3. Deletion analysis of BSLF1 showed that the region between amino acid 640 and 710 is important to the DUB activity on BFRF3. Taken together, BSLF1 plays a critical role on stabilizing the capsid proteins. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/57466 |
Fulltext Rights: | 有償授權 |
Appears in Collections: | 生化科技學系 |
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ntu-103-1.pdf Restricted Access | 2.69 MB | Adobe PDF |
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