Saito A, Fujii T, Yoneyama T, Miyashita K
National Institute of Agro-Environmental Sciences, 3-1-1 Kan-nondai, Tsukuba, Ibaraki 305-8604, Japan.
J Bacteriol. 1998 Jun;180(11):2911-4. doi: 10.1128/JB.180.11.2911-2914.1998.
Chitinase production in Streptomyces lividans is induced by chitin and repressed in the presence of glucose. A mutant of S. lividans TK24, strain G015, which was defective in glucose repression of chitinase production, was obtained by screening colonies for zones of clearing on colloidal chitin agar plates containing 1.0% (wt/vol) glucose. The transcriptional analysis of chiA in G015 with xylE, which encodes catechol 2,3-dioxygenase, as a reporter gene showed that the transcription from the chiA promoter of S. lividans TK24 occurred regardless of the presence of glucose. G015 was resistant to 2-deoxyglucose (2-DOG) and did not utilize glucose as a sole carbon source. When a DNA fragment containing glkA, a gene for glucose kinase, of Streptomyces coelicolor A3(2) was introduced into strain G015 on a low-copy-number plasmid, the sensitivity to 2-DOG, the ability to utilize glucose, and the glucose repression of chitinase production were restored. These results indicate that glkA is involved in glucose repression of chitinase production in S. lividans TK24.
天蓝色链霉菌中几丁质酶的产生受几丁质诱导，在葡萄糖存在时受到抑制。通过在含有1.0%（重量/体积）葡萄糖的胶体几丁质琼脂平板上筛选出有透明圈的菌落，获得了天蓝色链霉菌TK24的一个突变体G015，该突变体在几丁质酶产生的葡萄糖抑制方面存在缺陷。以编码儿茶酚2,3-双加氧酶的xylE作为报告基因，对G015中的chiA进行转录分析，结果表明，无论葡萄糖是否存在，天蓝色链霉菌TK24的chiA启动子都会发生转录。G015对2-脱氧葡萄糖（2-DOG）具有抗性，且不能利用葡萄糖作为唯一碳源。当将含有天蓝色链霉菌A3(2)的葡萄糖激酶基因glkA的DNA片段以低拷贝数质粒导入G015菌株时，其对2-DOG的敏感性、利用葡萄糖的能力以及几丁质酶产生的葡萄糖抑制作用均得以恢复。这些结果表明，glkA参与了天蓝色链霉菌TK24中几丁质酶产生的葡萄糖抑制过程。
