牛痘病毒鞘膜蛋白質 A27L 的結構與功能之分析

牛痘病毒鞘膜蛋白質 A27L 的結構與功能之分析

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近來研究發現 A27L 蛋白質對於 VV 在細胞中運送的過程扮演著重要 角色，因為當抑制 A27L 蛋白質表現時細胞內成熟病毒 (IMV) 的運送 也同時受到抑制，因為整個相關機制對 VV 散播非常重要，所以更加 深研究此議題的價值。

為研究 A27L 蛋白質在 IMV 運送機制中所扮演的角色，我製備了兩個 具有突變 A27L 基因的病毒， DA27L-VV 和 A27LKR-VV ，分別是針 對 A27L 蛋白質從 N 端第 21 至第 32 個胺基酸的部分 (GAG-binding d omain) 進行突變後所得之重組病毒。研究結果顯示所突變區域對於 I MV 的運送並不重要，可見得 A27L 蛋白質之 coiled-coil 結構區域即 可負責運送 IMV 。

Structural and Functional Analyses of Vacci nia Virus Envelope A27L Protein

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Vaccinia virus (VV) belongs to the poxvirus family and has a double-stranded DN A genome of 192Kb in size. VV contains an envelope and replicates in cytoplasm o f the infected cells. VV has a wide host range and infects various mammalian cell li nes as well as animals. Viral A27L gene encodes a 14kDa envelope protein that int eracts with cell surface heparan sulfate and is important for cell fusion. A27L protei n is also required for the formation of intracellular enveloped virus (IEV) from intra cellular mature virus (IMV) during virion morphogenesis.

Previous data suggested that A27L protein plays an additional role in VV transport in cells because when cells were infected with VV, under a condition that represses A27L expression, transport of IMV from intermediate compartment to Golgi appart ments was inhibited. Up to now the Golgi-targeting mechanism remains unknown.

In order to investigate the role of A27L protein in IMV transport , I generared two r

ecombinant viruses which contain mutations in A27L gene. One recombinant virus,

DA27L-VV, expresses a mutant A27L protein with N-terminal deletion to remove t

he GAG-binding domain. Another one, A27LKR-VV, specifically mutated amino a

cids K and R to N and S to eliminate positive changes within the GAG-binding do

main. Our results indicate that the N-terminal GAG-binding domain of A27L protei

n is not required for IMV transport and indicate that coiled-coil domain is nessary a

nd sufficient for this function.