AXY8 Encodes an α-Fucosidase, Underscoring the Importance of Apoplastic Metabolism on the Fine Structure of Arabidopsis Cell Wall Polysaccharides
AXY8 Encodes an α-Fucosidase, Underscoring the Importance of Apoplastic Metabolism on the Fine Structure of Arabidopsis Cell Wall Polysaccharides
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DOI：
10.1105/tpc.111.089193
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发表时间：
2011-11-01
期刊：
影响因子：
11.6
通讯作者：
Pauly, Markus
中科院分区：
文献类型：
--
作者：
Guenl, Markus;Neumetzler, Lutz;Pauly, Markus
一个拟南芥突变体的半纤维素木聚糖(XyG；AXY-8)的结构发生了改变，通过促进低聚糖质量图谱的正向遗传筛选进行了鉴定。Axy8表现出增加的XyG岩藻糖基化和出现野生型植物中不存在的XyG片段。AXY8被鉴定为编码作用于XyG的α-岩藻糖苷酶，以前被命名为FUC95A。绿色荧光蛋白融合定位研究和微粒体制剂中新生XyG的分析表明，该糖基水解酶主要作用于质外体中的XyG。对axy8中XyG的详细结构分析为岩藻糖苷酶在体内XyG代谢中的作用提供了独特的见解。遗传证据表明，质外体中糖基水解酶的活性是产生壁中XyG侧链异质性的主要原因。此外，在没有主要的质外体糖基水解酶的情况下，壁中的XyG结构主要由XXXG和XXFG亚基组成。
An Arabidopsis thaliana mutant with an altered structure of its hemicellulose xyloglucan (XyG; axy-8) identified by a forward genetic screen facilitating oligosaccharide mass profiling was characterized. axy8 exhibits increased XyG fucosylation and the occurrence of XyG fragments not present in the wild-type plant. AXY8 was identified to encode an alpha-fucosidase acting on XyG that was previously designated FUC95A. Green fluorescent protein fusion localization studies and analysis of nascent XyG in microsomal preparations demonstrated that this glycosylhydrolase acts mainly on XyG in the apoplast. Detailed structural analysis of XyG in axy8 gave unique insights into the role of the fucosidase in XyG metabolism in vivo. The genetic evidence indicates that the activity of glycosylhydrolases in the apoplast plays a major role in generating the heterogeneity of XyG side chains in the wall. Furthermore, without the dominant apoplastic glycosylhydrolases, the XyG structure in the wall is mainly composed of XXXG and XXFG subunits.