- 著者
-
奥島 実
SUGINO Dan
KOUNO Yoshio
NAKANO Shigeru
MIYAHARA Junichi
TODA Hisashi
KUBO Shigemasa
MATSUSHIRO Aizo
- 出版者
- Genetics Society of Japan
- 雑誌
- 遺伝学雑誌 (ISSN:0021504X)
- 巻号頁・発行日
- vol.66, no.2, pp.173-187, 1991
- 被引用文献数
-
8
18
A bacterial strain, which assimilated dextran and water-insoluble glucan produced by <i>Streptococcus mutans</i>, was isolated from soil. The bacterium produced and secreted potent dextranase activity, which was identified as <i>Arthrobacter sp</i>. and named CB-8. The dextranase was purified and some enzymatic properties were characterized. The enzyme efficiently decomposed the water-insoluble glucan as well as dextran. A gene library from the bacteria was constructed with <i>Escherichia coli</i>, using plasmid pUC19, and clones producing dextranase activity were selected. Based on the result of nucleotide sequencing analysis, it was deduced that the dextranase was synthesized in CB-8 cells as a polypeptide precursor consisting of 640 amino acid residues, including 49 N-terminal amino acid residues which could be regarded as a signal peptide. In the <i>E. coli</i> transformant, the dextranase activity was detected mostly in the periplasmic space. The gene for the dextranase was introduced into <i>Streptococcus sanguis</i>, using an <i>E. coli-S</i>. <i>sanguis</i> shuttle vector that contained the promoter sequence of a gene for glucosyltransferase derived from a strain of <i>S. mutans</i>. The active dextranase was also expressed and accumulated in <i>S. sanguis</i> cells.<br>