Gene cloning, expression and characterization of a new cold-active and salt-tolerant endo-β-1,4-xylanase from marine Glaciecola mesophila KMM 241
Gene cloning, expression and characterization of a new cold-active and salt-tolerant endo-β-1,4-xylanase from marine Glaciecola mesophila KMM 241
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DOI：
10.1007/s00253-009-2056-y
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发表时间：
2009-10-01
影响因子：
5
通讯作者：
Zhang, Yu-Zhong
中科院分区：
文献类型：
--
作者：
Guo, Bing;Chen, Xiu-Lan;Zhang, Yu-Zhong
虽然人们对木聚糖酶进行了大量的研究，但从海洋微生物中提取的木聚糖酶的报道还很少。从海洋细菌Glaciecola Mesophila KMM 241中克隆到一个新的木聚糖酶基因xynA。XynA基因全长1,272个碱基，编码423个氨基酸的木聚糖酶前体。在大肠杆菌BL21中表达的重组木聚糖酶XynA是一种相对分子质量为43 kDa的单体。在所鉴定的木聚糖酶中，XynA与黄杆菌的木聚糖酶同源性最高(46%)。菌株MSY2。XynA的最适pH为7.0，最适温度为30℃。XynA在4℃时保持23%的活性和27%的催化效率。XynA的热稳定性较低，在30A℃孵育60min后仍保持20%的活性，其表观熔点(T(M))为44.5A℃。XynA表现出较强的耐盐性，在0.5M的氯化钠溶液中活性最高，在2.5M的氯化钠溶液中保持90%的活性。这可能是第一个报道的耐盐性木聚糖酶。XynA是一种严格的内切β-1，4-木聚糖酶，需要至少四个糖基才能进行有效的切割。它能有效地将低聚木糖和木聚糖水解成木二糖和木三糖，而不产生木糖，这表明它在低聚木糖生产中具有潜在的潜力。
Although a lot of xylanases are studied, only a few xylanases from marine microorganisms have been reported. A new xylanase gene, xynA, was cloned from marine bacterium Glaciecola mesophila KMM 241. Gene xynA contains 1,272 bp and encodes a 423-amino acid xylanase precursor. The recombinant xylanase, XynA, expressed in Escherichia coli BL21 is a monomer with a molecular mass of 43 kDa. Among the characterized xylanases, XynA shares the highest identity (46%) to the xylanase from Flavobacterium sp. strain MSY2. The optimum pH and temperature for XynA is 7.0 and 30 A degrees C. XynA retains 23% activity and 27% catalytic efficiency at 4 A degrees C. XynA has low thermostability, remaining 20% activity after 60-min incubation at 30 A degrees C. Its apparent melting temperature (T (m)) is 44.5 A degrees C. These results indicate that XynA is a cold-active xylanase. XynA shows a high level of salt-tolerance, with the highest activity at 0.5 M NaCl and retaining 90% activity in 2.5 M NaCl. It may be the first salt-tolerant xylanase reported. XynA is a strict endo-beta-1,4-xylanase with a demand of at least four sugar moieties for effective cleavage. It efficiently hydrolyzes xylo-oligosaccharides and xylan into xylobiose and xylotriose without producing xylose, suggesting its potential in xylo-oligosaccharides production.