Burget E G, Reiter W D
Department of Molecular and Cell Biology, University of Connecticut, Storrs, Connecticut 06269, USA.
Plant Physiol. 1999 Oct;121(2):383-9. doi: 10.1104/pp.121.2.383.
To obtain information on the synthesis and function of arabinosylated glycans, the mur4 mutant of Arabidopsis was characterized. This mutation leads to a 50% reduction in the monosaccharide L-arabinose in most organs and affects arabinose-containing pectic cell wall polysaccharides and arabinogalactan proteins. Feeding L-arabinose to mur4 plants restores the cell wall composition to wild-type levels, suggesting a partial defect in the de novo synthesis of UDP-L-arabinose, the activated sugar used by arabinosyltransferases. The defect was traced to the conversion of UDP-D-xylose to UDP-L-arabinose in the microsome fraction of leaf material, indicating that mur4 plants are defective in a membrane-bound UDP-D-xylose 4-epimerase.
为了获取有关阿拉伯糖基化聚糖合成与功能的信息，对拟南芥的mur4突变体进行了表征。这种突变导致大多数器官中的单糖L-阿拉伯糖减少50%，并影响含阿拉伯糖的果胶细胞壁多糖和阿拉伯半乳聚糖蛋白。给mur4植株饲喂L-阿拉伯糖可使细胞壁组成恢复到野生型水平，这表明在阿拉伯糖基转移酶所使用的活化糖UDP-L-阿拉伯糖的从头合成中存在部分缺陷。该缺陷可追溯到叶片材料微粒体部分中UDP-D-木糖向UDP-L-阿拉伯糖的转化，这表明mur4植株在膜结合的UDP-D-木糖4-表异构酶方面存在缺陷。
