d-Xylose Isomerase from a Marine Bacterium, Vibrio sp. Strain XY-214, and d-Xylulose Production from β-1,3-Xylan
d-Xylose Isomerase from a Marine Bacterium, Vibrio sp. Strain XY-214, and d-Xylulose Production from β-1,3-Xylan
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DOI：
10.1007/s10126-011-9380-9
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发表时间：
2012-02
影响因子：
3
通讯作者：
Yoshiaki Umemoto;Toshiyuki Shibata;T. Araki
中科院分区：
文献类型：
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作者：
Yoshiaki Umemoto;Toshiyuki Shibata;T. Araki
来自海洋细菌Vibriosp的ThexylA基因。克隆了编码木糖异构酶（XylA）的XY-214菌株，并在大肠杆菌中表达。ThexylA基因由1，320-bp核苷酸组成，编码439个氨基酸的蛋白质，预测分子量为49，264。XylA被分类为II组木糖异构酶。估计天然XylA是分子量为190 kDa的同源四聚体。纯化的重组XylA在60°C和pH 7.5下表现出最大活性。对D-木糖和D-葡萄糖的表观Km值分别为7.93和187 mM。此外，我们进行了从β-1，3-木聚糖，一种主要的细胞壁多糖组分的杀手藻类杉叶蕨藻的d-木酮糖的生产。研究了弧菌β-1，3-木聚糖酶（TxyA）和β-1，3-木糖苷酶（XloA）的协同作用。菌株XY-214能有效地将β-1，3-木聚糖糖化为d-木糖，然后用来自菌株XY-214的XylA将d-木糖转化为d-木酮糖。发现在4 mM四硼酸钠存在下孵育2小时后，通过XylA将d-木糖转化为d-木酮糖的转化率为约40%。这些结果表明Vibriosp.菌株XY-214是利用β-1，3-木聚糖生产β-木酮糖有用工具。由于木酮糖可以作为酿酒酵母发酵乙醇的原料，本研究为β-1，3-木聚糖发酵生产乙醇提供了依据。
ThexylAgene from a marine bacterium,Vibriosp. strain XY-214, encodingd-xylose isomerase (XylA) was cloned and expressed inEscherichia coli. ThexylAgene consisted of 1,320-bp nucleotides encoding a protein of 439 amino acids with a predicted molecular weight of 49,264. XylA was classified into group II xylose isomerases. The native XylA was estimated to be a homotetramer with a molecular mass of 190 kDa. The purified recombinant XylA exhibited maximal activity at 60°C and pH 7.5. Its apparentKmvalues ford-xylose andd-glucose were 7.93 and 187 mM, respectively. Furthermore, we carried outd-xylulose production from β-1,3-xylan, a major cell wall polysaccharide component of the killer algaCaulerpa taxifolia. The synergistic action of β-1,3-xylanase (TxyA) and β-1,3-xylosidase (XloA) fromVibriosp. strain XY-214 enabled efficient saccharification of β-1,3-xylan tod-xylose.d-Xylose was then converted tod-xylulose by using XylA from the strain XY-214. The conversion rate ofd-xylose tod-xylulose by XylA was found to be approximately 40% in the presence of 4 mM sodium tetraborate after 2 h of incubation. These results demonstrated that TxyA, XloA, and XylA fromVibriosp. strain XY-214 are useful tools ford-xylulose production from β-1,3-xylan. Becaused-xylulose can be used as a source for ethanol fermentation by yeastSaccharomyces cerevisiae, the present study will provide a basis for ethanol production from β-1,3-xylan.