Nakagawa N, Sakurai N
Faculty of Integrated Arts & Sciences, Hiroshima University, Higashi-Hiroshima, Japan.
Plant Cell Physiol. 1998 Jul;39(7):779-85. doi: 10.1093/oxfordjournals.pcp.a029434.
The biochemical analysis of cellulose biosynthesis by plants has been a difficult problem due to the lack of a reliable assay procedure for cellulose synthase activity. Recently, the celA1 gene was cloned from cotton fiber, and this gene was identified from the rsw1 mutant of Arabidopsis as a catalytic subunit of cellulose synthase (Arioli et al. 1998). The cloning of these genes enables us to obtain specific antibodies against cellulose synthase. A highly specific antibody against celA1 protein was prepared and used to detect the protein from microsomal fraction of tobacco BY-2 cells. The quantity of celA1 protein in microsomal fraction of normal BY-2 cells was under the detection limit, although they contained a large quantity of cellulose. In contrast, cells habituated to 1 microM DCB (a specific inhibitor of cellulose biosynthesis) produced 1/10 of cellulose content of the normal cells, but had much more celA1 protein than the normal cells. The amount of polysaccharides in the EDTA-soluble fraction was relatively increased in habituated cells. The results suggest that celA1 protein is stabilized upon DCB binding and that the crystallization of cellulose microfibrils is inhibited simultaneously.
由于缺乏可靠的纤维素合酶活性检测方法，植物纤维素生物合成的生化分析一直是个难题。最近，从棉花纤维中克隆出了celA1基因，该基因在拟南芥的rsw1突变体中被鉴定为纤维素合酶的催化亚基（Arioli等人，1998年）。这些基因的克隆使我们能够获得针对纤维素合酶的特异性抗体。制备了一种针对celA1蛋白的高度特异性抗体，并用于检测烟草BY-2细胞微粒体部分的该蛋白。正常BY-2细胞微粒体部分的celA1蛋白量低于检测限，尽管它们含有大量纤维素。相比之下，适应1 microM DCB（纤维素生物合成的特异性抑制剂）的细胞产生的纤维素含量为正常细胞的1/10，但celA1蛋白比正常细胞多得多。在适应细胞中，EDTA可溶性部分的多糖量相对增加。结果表明，celA1蛋白在与DCB结合后会稳定下来，同时纤维素微纤丝的结晶受到抑制。
