假纖毛蛋白XpsK在十字花科黑腐病菌Type II蛋白分泌系統中的功能探討

中山醫學大學機構典藏 CSMUIR > 醫學院 > 生化微生物免疫研究所 > 研究計劃 > Item 310902500/3247

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Title:	假纖毛蛋白XpsK在十字花科黑腐病菌Type II蛋白分泌系統中的功能探討 Roles of Pseudopilin XpsK in Type II Prorein Secretion Pathway from Xanthomonas Campestris
Authors:	陳凌雲 Chen, Ling-Yun
Contributors:	中山醫學院生化學科
Keywords:	類纖毛蛋白;格蘭氏陰性菌外膜蛋白分泌機器 Pilus-like protein;Gram-negtive bacteria outer membrane protein secretion machinery
Date:	2007
Issue Date:	2010-12-16T03:47:49Z (UTC)
Abstract:	十字花科黑腐病菌為格蘭氏陰性菌的一種，會利用第二型分泌系統分泌蛋白而感染宿主。分泌的蛋白會先藉由Sec-dependent 系統到達膜間質，再由一群12~14 個蛋白所組成的分泌機器將分泌蛋白運送出細胞外。其中XpsG、H、I、J 和K 蛋白NH2-端與第四型纖毛生成系統中的纖毛組成蛋白有同源性，推測可在內外膜之間組裝成類纖毛構造，並推動分泌蛋白進入外膜通道。過去的研究發現XpsG 蛋白是類纖毛的主要組成，且橫跨於內外膜之間，另外，XpsH 可調節XpsG 與XpsJ 之間的交互作用，並推測類纖毛蛋白的排列順序為psG-XpsI-XpsH-XpsJ。由於XpsK 抗體已製備完成，因此本實驗藉由鎳離子親和性管柱探討五個類纖毛蛋白XpsG、H、I、J 和K 在各個缺損株中的交互作用情形。結果發現XpsI可以抑制XpsH 與XpsJ 彼此間的交互作用，說明了XpsI 可能扮演一個會與XpsH 競爭XpsJ的負調控角色。另外，發現XpsK 可促進XpsI 與XpsJ 彼此間的交互作用，說明XpsK 可能位於XpsI 與XpsJ 之間而扮演一個正調控的角色。同時也發現XpsH、XpsI 與XpsK 可能以兩兩結合(XpsH-XpsI、XpsH-XpsK 和XpsI-XpsK)的形式出現。綜合以上的結果推測類纖毛的生合成遠比想像中還要複雜，需要更多實驗加以釐清。 Keywords: pilus-like protein, Gram-negtive bacteria outer membrane protein secretion machinery Xanthomonas campestris pv. Campestris is one of the Gram-negtive bacteria which secretes protein to infect plants by typeⅡ secretion system. The secreted protein can reach to periplasm by the Sec-dependent system, and to export from cellular matrix by a machine composed of 12~14 proteins. The N terminal of XpsG, H, I , J and K protein are homologous with the pilin of type Ⅳ secretion system, those are predicted to be assembled into a pilus-like structure between the cytoplasmic and outer membrane. The pseudopilus is presumed to push exproteins into the outer membrane. On previous studys showed that XpsG was a mainly composed of pseudopilus to span between inner and outer membrane, and could regulate the interaction between XpsG and XpsJ,and thought that XpsG, I, H and J should act sequentially in such order. We have prepared specific antibody against XpsK that be used to analyze the interaction between XpsG、H、I、J and K in various bacterial strains with different xps gene knockout after Ni2+ affinity chromatography.Result revealed that XpsI could inhibit the interaction between XpsH and XpsJ, and act as a negative regulator. XpsK could promote the interaction between XpsI and XpsJ, act as a positive regulator. Take together, we believed that XpsG and XpsJ are located at a extremity of pseudopilin complex , and there are three interaction forms between XpsH, I and K , including XpsH-XpsI, XpsH-XpsK and XpsI-XpsK. We believe that the copmposed of the pseudopilus is a complicated mechanism, and need more experiments to explain any possibility.
URI:	https://ir.csmu.edu.tw:8080/handle/310902500/3247
Appears in Collections:	[生化微生物免疫研究所] 研究計劃

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