An unusual xylan in Arabidopsis primary cell walls is synthesised by GUX3, IRX9L, IRX10L and IRX14.
An unusual xylan in Arabidopsis primary cell walls is synthesised by GUX3, IRX9L, IRX10L and IRX14.
复制标题
DOI：
10.1111/tpj.12898
复制
发表时间：
2015-08
期刊：
影响因子：
--
通讯作者：
Dupree P
中科院分区：
文献类型：
--
作者：
Mortimer JC;Faria-Blanc N;Yu X;Tryfona T;Sorieul M;Ng YZ;Zhang Z;Stott K;Anders N;Dupree P
木聚糖是许多植物初级和次生细胞壁的重要组成部分。然而，双子叶植物初生细胞壁中木聚糖的结构和功能还不是很清楚。在这里，我们描述了一种木聚糖，它是在拟南芥初级细胞壁中丰富的组织中特有的。与前面描述的木聚糖不同，这种木聚糖携带1-2连接到α-1，2-d-葡萄糖醛酸(GLCA)侧链的戊糖，位于β-1，4-Xyl主干上。沿着主干每六个木糖基的GLCA取代的频繁和精确的规则间隔也不同于以前在次生细胞壁木聚糖中观察到的。分子遗传学、体外分析和表达数据表明，IRX9L、IRX10L和IRX14是初级细胞壁合成组织中合成木聚糖骨架所必需的。IRX9和IRX10不参与初级细胞壁木聚糖的合成，但可与IRX9L和IRX10L功能互换。GUX3是唯一一种在木聚糖上添加Glca修饰所需的葡萄糖醛酸基转移酶。原生和次生细胞壁中木聚糖结构的差异可能反映了不同的木聚糖在与其他细胞壁成分的交联和相互作用中所起的作用。
Xylan is a crucial component of many plant primary and secondary cell walls. However, the structure and function of xylan in the dicotyledon primary cell wall is not well understood. Here, we characterized a xylan that is specific to tissues enriched in Arabidopsis primary cell walls. Unlike previously described xylans, this xylan carries a pentose linked 1–2 to the α-1,2-d-glucuronic acid (GlcA) side chains on the β-1,4-Xyl backbone. The frequent and precisely regular spacing of GlcA substitutions every six xylosyl residues along the backbone is also unlike that previously observed in secondary cell wall xylan. Molecular genetics, in vitro assays, and expression data suggest that IRX9L, IRX10L and IRX14 are required for xylan backbone synthesis in primary cell wall synthesising tissues. IRX9 and IRX10 are not involved in the primary cell wall xylan synthesis but are functionally exchangeable with IRX9L and IRX10L. GUX3 is the only glucuronyltransferase required for the addition of the GlcA decorations on the xylan. The differences in xylan structure in primary versus secondary cell walls might reflect the different roles in cross-linking and interaction with other cell wall components.