Department of Biotechnology, College of Natural Resources and Life Science, Dong-A University, Busan 604-714, Korea.
J Microbiol Biotechnol. 2013 Mar;23(3):397-404. doi: 10.4014/jmb.1212.12017.
Paenibacillus xylanilyticus KJ-03 was isolated from soil samples obtained from a field with Amorphophallus konjac plants. A gene encoding xylanase was isolated from KJ-03 and cloned using a fosmid library. The xynA gene encodes xylanase; it consists of 1,035 bp and encodes 345 amino acids. The amino acid sequence deduced from the P. xylanilyticus KJ-03 xylanase showed 81% and 69% identities with those deduced from the P. polymyxa E681 and Paenibacillus sp. HPL-001 xylanases, respectively. The xynA gene comprises a single domain, consisting of a catalytic domain of the glycosyl hydrolase (GH) 10 family. The xynA gene was expressed in Escherichia coli BL21 (trxB), and the recombinant xylanase was purified by Niaffinity chromatography. The purified xylanase showed optimum activity with birchwood xylan as a substrate at 40°C and pH 7.4. Treatment with Mg(2+) and Li(+) showed a slight decrease in XynA activity; however, treatment with 5 mM Cu(2+) completely inhibited its activity. The results of the thin layer chromatography analysis indicated that the major hydrolysis product was xylobiose and small amounts of xylose and xylotriose. XynA showed increased activity with oat spelt xylan and birchwood xylan, but showed only slight activity with locust bean gum.
从魔芋田的土壤样本中分离到了一株嗜木聚糖芽孢杆菌（Paenibacillus xylanilyticus）KJ-03。该菌可产生木聚糖酶，本研究通过构建宏基因组文库克隆了该酶的编码基因 xynA。xynA 基因全长 1035 bp，编码 345 个氨基酸。推导的 P. xylanilyticus KJ-03 木聚糖酶的氨基酸序列与 P. polymyxa E681 和 Paenibacillus sp. HPL-001 木聚糖酶的同源性分别为 81%和 69%。xynA 基因包含一个单一的结构域，由糖苷水解酶（GH）10 家族的催化结构域组成。xynA 基因在大肠杆菌 BL21（trxB）中表达，重组木聚糖酶通过 Ni-NTA 亲和层析进行纯化。该酶以桦木木聚糖为底物时，在 40°C 和 pH7.4 下具有最佳活性。Mg2+和 Li+处理对 XynA 活性略有降低，而 5 mM Cu2+处理则完全抑制其活性。薄层层析分析结果表明，主要的水解产物是木二糖，还有少量的木糖和木三糖。XynA 对燕麦木聚糖和桦木木聚糖的活性较高，但对槐豆胶的活性仅略有增加。
