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標題: 環狀芽苞桿菌WL-12的幾丁質分解酵素A1基因在啤酒酵母菌內之表 現
Expression of Bacillus circulans WL-12 chitinase A1 gene in Saccharomyces cerevisiae
作者: 徐光明
Hsu, Kuang-Ming
關鍵字: chitinase A1;幾丁質分解酵素A1;Bacillus circulans WL-12;Saccharomyces cerevisiae;electroporation;環狀芽苞桿菌WL-12;啤酒酵母菌;電穿孔轉形
出版社: 植物學系
環狀芽苞桿菌 (Bacillus circulans) WL-12 為革蘭氏陽性桿菌,最先是
生 A1、A2、B1、B2、C 及 D 六種不同的幾丁質分解酵素,其中以 A1 為
關鍵酵素,幾丁質分解酵素 A1 基因 (chiA1) 已被定序分析。由於幾丁
質分解酵素具有分解真菌細胞壁幾丁質的特性, 因此本實驗主要目的即
以此菌株的 chiA1 基因為材料,將這基因轉形至大腸桿菌 (Escherichia
coli) 中,除了探討此基因在大腸桿菌中的表現情形外,並更進一步將此
段 chiA1 基因轉形至酵母菌中,希望能使其在酵母菌的系統中大量表現
,以作為生物防治之基礎。 本實驗室前人首先依 Watanabe 等人的結果
(Watanabe et al., 1990 b ),根據 chiA1 基因的序列,在 5( 端與 3(
端各設計一條 26 個鹼基的引子,以 PCR 合成出一段約 2.1 Kb 之 ORF
,將其連接於 pKK223-3 載體,成功地構築一個 pKK-chiA1 重組質體,
且轉形至大腸桿菌 (E. coli ) HB101 中。本實驗即利用此 pKK-chiA1
重組質體為材料,再將此chiA1 基因從 pKK-chiA1 重組質體中切割出來
,連接於另一 YEp352 載體且轉形至大腸桿菌 (E. coli) JM109 (DE3),
將其培養在 LA-chitin 培養基,培養 3 日後形成澄清環。另外,為了更
進一步將 chiA1 基因轉形至酵母菌中表現,因此連接chiA1 基因於另一
pAAH5酵母菌表現載體,成功地構築另一個 pAAH5-chiA1 重組質體,並且
利用電穿孔 (electroporation) 方式將此重組質體送至啤酒酵母菌
(Saccharomyces cerevisiae ) AH22中,並且以 (YNB+histidine) 選擇
性培養基進行篩選。將酵母菌轉形株 pAAH5-chiA1 培養在 YPD-chitin
培養基中,於 30℃ 中培養 5 日後開始有澄清環形成。此外,在測定幾
丁質分解酵素活性的實驗中,發現酵母菌轉形株 pAAH5-chiA1有很高的幾
丁質分解酵素的活性,。由此實驗結果,可知道 Bacillus circulans
WL-12 的 chiA1 基因,不僅能在原核生物 (如 E. coli) 中表現,也能
在真核生物 (如 Saccharomyces cerevisiae) 中表現。

Bacillus circulans WL-12, originally isolated from soil with
yeast cell wall, is a gram positive bacterium which can degrade
fungal cell wall. It can produce six different kinds of
chitinase including A1, A2, B1, B2, C and D. Chitinase A1 is a
key enzyme of chitinase system of B. circulans WL-12, and
chitinase A1 gene (chiA1) have already been cloned and
sequenced. Chitinase has a property of degrading fungal cell
wall , so the main purpose of this study is to transform chiA1
gene into E. coli. Besides discussing the expression of chiA1
gene in E. coli, we go further to transform chiA1 gene into
yeast, to make its expression numerously as the basis of bio-
control. Accoding to the reports by Watanabe et al.
(Watanabe et al., 1990 b), the predecessor of our laboratory
designed two primers each on the opposite terminal of chiA1 gene
ORF (open-reading frame), and had synthesized the chiA1 gene by
PCR. The synthesized chiA1 gene was inserted into pKK223-3
vector. Then, the successfully constructed pKK-chiA1 plasmid was
transformed into E. coli HB101.The chiA1 gene was isolated from
pKK-chiA1 plasmid and religated with YEp352 vector, then
transformed into E. coli JM109 (DE3).The clear zones appeared
around bacterial colonies after 3 day incubation. Besides, we go
further to transform chiA1 gene into yeast. The chiA1 gene was
eluted from YEp352-chiA1 again, and ligated with pAAH5
expression vector. Then, transformed into Saccharomyces
cerevisiae AH22 by electroporation. The transformants were
screened on the YNB-histidin selective medium. Transformants
containing pAAH5-chiA1 plasmid were selected out from YPD-chitin
medium, the clear zones was observed after 5 day incubation at
30℃. Analysis the activity of chitinase indicated that pAAH5-
chiA1 transformant have high activity of chitinase. So, we came
to the conclusion that the chiA1 gene of Bacillus circulans
WL-12 not only expresses in procaryotes (such as E. coli), but
also expresses in eukaryotes (such as Saccharomyces cerevisiae).
Appears in Collections:生命科學系所

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