The carbohydrate-binding module (CBM)-like sequence is crucial for rice CWA1/BC1 function in proper assembly of secondary cell wall materials
The carbohydrate-binding module (CBM)-like sequence is crucial for rice CWA1/BC1 function in proper assembly of secondary cell wall materials
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DOI：
10.4161/psb.5.11.13342
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发表时间：
2010-11
影响因子：
2.9
通讯作者：
Kanna Sato;S. Ito;T. Fujii;Ryu Suzuki;Sachi Takenouchi;Satoshi Nakaba;R. Funada;Y. Sano;S. Kajita;Kitano Hidemi;Y. Katayama
中科院分区：
文献类型：
--
作者：
Kanna Sato;S. Ito;T. Fujii;Ryu Suzuki;Sachi Takenouchi;Satoshi Nakaba;R. Funada;Y. Sano;S. Kajita;Kitano Hidemi;Y. Katayama
我们最近报道了cwa 1突变干扰了水稻节间皮层纤维次生细胞壁物质的沉积和组装。基因分析表明，cwa 1与bc 1等位，bc 1编码糖基磷脂酰肌醇（GPI）锚定的COBRA-like蛋白，与拟南芥COBRA-like 4（COBL 4）和玉米脆茎2（Bk 2）同源性最高。我们的研究结果表明，CWA 1/BC 1在适当的位置组装次生细胞壁材料中发挥作用，使高度有序的次生细胞壁结构与坚实和灵活的节间在水稻中的合成。CWA 1/BC 1的N-末端氨基酸序列，以及它的直系同源物（COBL 4，Bk 2）和其他类似于水稻BC 1的蛋白质，显示出弱的相似性，家庭II碳水化合物结合模块（CBM 2）的几种细菌纤维素酶。为了研究CWA 1/BC 1的CBM样序列在次生细胞壁材料组装中的重要性，将CBM样序列中对碳水化合物结合重要的Trp残基替换为瓦尔残基并引入到CWA 1突变体中。具有突变序列的CWA 1/BC 1没有补充在CWA 1突变体中观察到的异常次生细胞壁，这表明CBM样序列对于CWA 1/BC 1的正常功能是必需的，包括次生细胞壁材料的组装。
We recently reported that the cwa1 mutation disturbed the deposition and assembly of secondary cell wall materials in the cortical fiber of rice internodes. Genetic analysis revealed that cwa1 is allelic to bc1, which encodes glycosylphosphatidylinositol (GPI)-anchored COBRA-like protein with the highest homology to Arabidopsis COBRA-like 4 (COBL4) and maize Brittle Stalk 2 (Bk2). Our results suggested that CWA1/BC1 plays a role in assembling secondary cell wall materials at appropriate sites, enabling synthesis of highly ordered secondary cell wall structure with solid and flexible internodes in rice. The N-terminal amino acid sequence of CWA1/BC1, as well as its orthologs (COBL4, Bk2) and other BC1-like proteins in rice, shows weak similarity to a family II carbohydrate-binding module (CBM2) of several bacterial cellulases. To investigate the importance of the CBM-like sequence of CWA1/BC1 in the assembly of secondary cell wall materials, Trp residues in the CBM-like sequence, which is important for carbohydrate binding, were substituted for Val residues and introduced into the cwa1 mutant. CWA1/BC1 with the mutated sequence did not complement the abnormal secondary cell walls seen in the cwa1 mutant, indicating that the CBM-like sequence is essential for the proper function of CWA1/BC1, including assembly of secondary cell wall materials.