Characterization of α- L -arabinofuranosidase related to the secondary cell walls formation in Arabidopsis thaliana
Characterization of α- L -arabinofuranosidase related to the secondary cell walls formation in Arabidopsis thaliana
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与拟南芥次生细胞壁形成相关的 α-L-阿拉伯呋喃糖苷酶的表征
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发表时间：
2010
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通讯作者：
S. Kaneko
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作者：
H. Ichinose;N. Nishikubo;T. Demura;S. Kaneko
编码51 α-L-阿拉伯呋喃糖苷酶家族的基因（At 3g 10740）在拟南芥木质部导管形成阶段特异表达。为了研究该酶在木质部导管形成中的作用，在毕赤酵母中表达了重组蛋白，并对其性质进行了表征。该酶在pH 4.5和50°C下表现出最佳活性，并在30°C下在pH 4.0-7.0范围内稳定。该酶能从对硝基苯基-α-L-阿拉伯呋喃糖苷、合成的阿拉伯呋喃糖苷、阿拉伯木寡糖和含阿拉伯糖的多糖中释放L-阿拉伯糖。该酶水解对硝基苯基-α-L-阿拉伯呋喃糖苷，但不水解任何其他对硝基苯基糖苷，对对硝基苯基-α-L-阿拉伯呋喃糖苷的比活性为1.2单位mg−1。在阿拉伯呋喃糖苷的合成区域异构体中，该酶水解两个α-L-阿拉伯呋喃糖残基之间的所有键，顺序为：α-1，5-键>α-1，2-键>α-1，3-键。该酶水解阿拉伯聚糖、阿拉伯树胶、玉米船体阿拉伯木聚糖和小麦阿拉伯木聚糖。该酶对低聚糖的活性高于对多糖的活性。此外，该酶还优先水解阿拉伯木寡糖，如O-α-L-阿拉伯呋喃糖基-1，3-O-β-D-吡喃木糖基-1，4-D-吡喃木糖苷和O-β-D-吡喃木糖基-1，4-[O-α-L-阿拉伯呋喃糖基-1，3]-O-β-D-吡喃木糖基-1，4-O-β-D-吡喃木糖苷，它们是由家族10木聚糖酶产生的木聚糖的水解产物，与其对阿拉伯呋喃糖苷的活性相比。这些数据表明，在木质部导管形成过程中，该酶与家族10木聚糖酶一起参与木聚糖结构的修饰。
A gene encoding a family 51 α-L-arabinofuranosidase (At3g10740) is specifically expressed at the stage of xylem vessel formation in Arabidopsis thaliana. To investigate the role of the enzyme in the xylem vessel formation, the recombinant protein was expressed in Pichia pastoris and the properties were characterized. The enzyme showed optimal activity at pH 4.5 and 50°C and was stable over the pH range of 4.0–7.0 under 30°C. The enzyme released L-arabinose from p-nitrophenyl-α-L-arabinofuranoside, synthetic arabinofuranobiosides, arabinoxylo-oligosaccharides and arabinose-containing polysaccharides. The enzyme hydrolyzed p-nitrophenyl-α-L-arabinofuranoside but did not hydrolyze any other p-nitrophenyl-glycosides, and the specific activity for p-nitrophenyl-α-L-arabinofuranoside was 1.2 units mg−1. Among the synthetic regioisomers of arabinofuranobiosides, the enzyme hydrolyzed all linkages that can occur between two α-L-arabinofuranosyl residues in the following order: α-1,5-linkage>α-1,2-linkage>α-1,3-linkage. The enzyme hydrolyzed arabinan, gum arabic, corn hull arabinoxylan, and wheat arabinoxylan. The enzyme showed higher activity for oligosaccharides than for polysaccharides. Furthermore, the enzyme preferentially hydrolyzed arabinoxylo-oligosaccharides such as O-α-L-arabinofuranosyl-1,3-O-β-D-xylopyranosyl-1,4-D-xylopyranoside and O-β-D-xylopyranosyl-1,4-[O-α-L-arabinofuranosyl-1,3]-O-β-D-xylopyranosyl-1,4-O-β-D-xylopyranoside, which were the hydrolysis products of xylan generated by a family 10 xylanase, in comparison to its activity for arabinofuranobiosides. These data suggest that the enzyme is involved in the modification of the structure of xylan together with family 10 xylanases during the xylem vessel formation.