The biosynthesis, degradation, and function of cell wall ß-xylosylated xyloglucan mirrors that of arabinoxyloglucan
The biosynthesis, degradation, and function of cell wall ß-xylosylated xyloglucan mirrors that of arabinoxyloglucan
复制标题
细胞壁α-木糖基化木葡聚糖的生物合成、降解和功能与阿拉伯木葡聚糖相似
DOI：
10.1111/nph.19305
复制
发表时间：
2023
期刊：
影响因子：
9.4
通讯作者：
Wilson L
中科院分区：
文献类型：
--
作者：
Wilson L
木葡聚糖是许多初生细胞壁和人类饮食中丰富的多糖。用更多的糖修饰其α-木糖基侧链对植物生长至关重要，即使糖本身在物种之间变化很大。杜鹃花科植物-在人类饮食中普遍存在-表现出β 1，2-连接的木糖装饰。负责添加这些木糖装饰的生物合成酶以及在人类肠道中去除它们的水解酶尚未鉴定。GT 47木葡聚糖糖基转移酶候选物在拟南芥中表达，并通过电泳、质谱和核磁共振（NMR）分析了来自转基因壁材料的木葡聚糖酶产物。采用比色法和荧光法测定了肠道细菌水解酶BoGH 43 A和BoGH 43 B对合成糖苷和木葡聚糖寡糖的活性。CcXBT 1是一种来源于咖啡的木葡聚糖β-木糖基转移酶，可以修饰拟南芥木葡聚糖，并恢复半乳糖基转移酶突变体的生长。RelatedVmXST 1是来自蔓越莓的弱活性木葡聚糖α-阿拉伯呋喃糖基转移酶。BoGH 43 A同时水解α-阿拉伯呋喃糖基化和β-木糖基化低聚糖。CcXBT 1在咖啡中的存在和BoGH 43 A的混杂表明β-木糖基化木葡聚糖不仅比想象的更广泛，而且还可能滋养有益的肠道细菌。转移酶特异性的进化不稳定性和水解酶特异性的缺乏暗示，对于酶，木糖苷和阿拉伯呋喃糖苷是紧密结合的。
Xyloglucan is an abundant polysaccharide in many primary cell walls and in the human diet. Decoration of its α‐xylosyl sidechains with further sugars is critical for plant growth, even though the sugars themselves vary considerably between species. Plants in the Ericales order – prevalent in human diets – exhibit β1,2‐linked xylosyl decorations. The biosynthetic enzymes responsible for adding these xylosyl decorations, as well as the hydrolases that remove them in the human gut, are unidentified.GT47 xyloglucan glycosyltransferase candidates were expressed in Arabidopsis andendo‐xyloglucanase products from transgenic wall material were analysed by electrophoresis, mass spectrometry, and nuclear magnetic resonance (NMR) spectroscopy. The activities of gut bacterial hydrolasesBoGH43A andBoGH43B on synthetic glycosides and xyloglucan oligosaccharides were measured by colorimetry and electrophoresis.CcXBT1 is a xyloglucan β‐xylosyltransferase from coffee that can modify Arabidopsis xyloglucan and restore the growth of galactosyltransferase mutants. RelatedVmXST1 is a weakly active xyloglucan α‐arabinofuranosyltransferase from cranberry.BoGH43A hydrolyses both α‐arabinofuranosylated and β‐xylosylated oligosaccharides.CcXBT1's presence in coffee andBoGH43A's promiscuity suggest that β‐xylosylated xyloglucan is not only more widespread than thought, but might also nourish beneficial gut bacteria. The evolutionary instability of transferase specificity and lack of hydrolase specificity hint that, to enzymes, xylosides and arabinofuranosides are closely resemblant.