Busse-Wicher Marta, Grantham Nicholas J, Lyczakowski Jan J, Nikolovski Nino, Dupree Paul
Department of Biochemistry and Leverhulme Centre for Natural Material Innovation, University of Cambridge, Cambridge CB2 1QW, U.K.
Biochem Soc Trans. 2016 Feb;44(1):74-8. doi: 10.1042/BST20150183.
The molecular architecture of plant secondary cell walls is still not resolved. There are several proposed structures for cellulose fibrils, the main component of plant cell walls and the conformation of other molecules is even less well known. Glucuronic acid (GlcA) substitution of xylan (GUX) enzymes, in CAZy family glycosyl transferase (GT)8, decorate the xylan backbone with various specific patterns of GlcA. It was recently discovered that dicot xylan has a domain with the side chain decorations distributed on every second unit of the backbone (xylose). If the xylan backbone folds in a similar way to glucan chains in cellulose (2-fold helix), this kind of arrangement may allow the undecorated side of the xylan chain to hydrogen bond with the hydrophilic surface of cellulose microfibrils. MD simulations suggest that such interactions are energetically stable. We discuss the possible role of this xylan decoration pattern in building of the plant cell wall.
植物次生细胞壁的分子结构仍未得到解析。对于植物细胞壁的主要成分纤维素微纤丝，有几种不同的结构模型被提出，而其他分子的构象则更是鲜为人知。在碳水化合物活性酶（CAZy）家族糖基转移酶（GT）8中的木聚糖葡萄糖醛酸（GlcA）取代（GUX）酶，能够以各种特定的GlcA模式修饰木聚糖主链。最近发现，双子叶植物木聚糖有一个结构域，其侧链修饰分布在主链（木糖）的每隔一个单元上。如果木聚糖主链的折叠方式与纤维素中的葡聚糖链（双螺旋）相似，那么这种排列方式可能会使木聚糖链未被修饰的一侧与纤维素微纤丝的亲水表面形成氢键。分子动力学（MD）模拟表明，这种相互作用在能量上是稳定的。我们讨论了这种木聚糖修饰模式在植物细胞壁构建中的可能作用。
