Feed Research Institute, Beijing, People's Republic of China.
J Ind Microbiol Biotechnol. 2010 Feb;37(2):187-94. doi: 10.1007/s10295-009-0662-4. Epub 2009 Nov 16.
We have identified a highly pH-adaptable and stable xylanase (XynA4) from the thermoacidophilic Alicyclobacillus sp. A4, a strain that was isolated from a hot spring in Yunnan Province, China. The gene (xynA4) that encodes this xylanase was cloned, sequenced, and expressed in Escherichia coli. It encodes a 338-residue polypeptide with a calculated molecular mass of 42.5 kDa. The deduced amino acid sequence is most similar to (53% identity) an endo-1,4-beta-xylanase from Geobacillus stearothermophilus that belongs to family 10 of the glycoside hydrolases. Purified recombinant XynA4 exhibited maximum activity at 55 degrees C and pH 7.0, had broad pH adaptability (>40% activity at pH 3.8-9.4) and stability (retaining >80% activity after incubation at pH 2.6-12.0 for 1 h at 37 degrees C), and was highly thermostable (retaining >90% activity after incubation at 60 degrees C for 1 h at pH 7.0). These properties make XynA4 promising for application in the paper industry. This is the first report that describes cloning and expression of a xylanase gene from the genus Alicyclobacillus.
我们从嗜酸耐热的 Alicyclobacillus sp. A4 中鉴定出一种高度适应 pH 值且稳定的木聚糖酶（XynA4）。该菌株是从中国云南省的一处温泉中分离得到的。编码该木聚糖酶的基因（xynA4）已被克隆、测序并在大肠杆菌中表达。它编码一个 338 个残基的多肽，计算分子量为 42.5 kDa。推断的氨基酸序列与属于糖苷水解酶家族 10 的 Geobacillus stearothermophilus 的内切 1,4-β-木聚糖酶最相似（53%的同一性）。纯化的重组 XynA4 在 55°C 和 pH 7.0 时表现出最大活性，具有广泛的 pH 适应性（在 pH 3.8-9.4 时具有>40%的活性）和稳定性（在 37°C 下孵育 1 小时，在 pH 2.6-12.0 时保留>80%的活性），并且具有很高的热稳定性（在 pH 7.0 下孵育 1 小时，在 60°C 时保留>90%的活性）。这些特性使 XynA4 在造纸工业中有很好的应用前景。这是首次报道从 Alicyclobacillus 属克隆和表达木聚糖酶基因。
