Dilokpimol Adiphol, Geshi Naomi
Department of Plant and Environmental Sciences; University of Copenhagen; Frederiksberg C, Denmark.
Plant Signal Behav. 2014;9(6):e28891. doi: 10.4161/psb.28891.
Arabinogalactan proteins are abundant cell-surface proteoglycans in plants and are involved in many cellular processes including somatic embryogenesis, cell-cell interactions, and cell elongation. We reported a glucuronosyltransferase encoded by Arabidopsis AtGlcAT14A, which catalyzes an addition of glucuronic acid residues to β-1,3- and β-1,6-linked galactans of arabinogalactan (Knoch et al. 2013). The knockout mutant of this gene resulted in the enhanced growth rate of hypocotyls and roots of seedlings, suggesting an involvement of AtGlcAT14A in cell elongation. AtGlcAt14A belongs to the family GT14 in the Carbohydrate Active Enzyme database (CAZy; www.cazy.org), in which a total of 11 proteins, including AtGLCAT14A, are classified from Arabidopsis thaliana. In this paper, we report the enzyme activities for the rest of the Arabidopsis GT14 isoforms, analyzed in the same way as for AtGlcAT14A. Evidently, two other Arabidopsis GT14 isoforms, At5g15050 and At2g37585, also possess the glucuronosyltransferase activity adding glucuronic acid residues to β-1,3- and β-1,6-linked galactans. Therefore, we named At5g15050 and At2g37585 as AtGlcAT14B and AtGlcAT14C, respectively.
阿拉伯半乳聚糖蛋白是植物中丰富的细胞表面蛋白聚糖，参与许多细胞过程，包括体细胞胚胎发生、细胞间相互作用和细胞伸长。我们报道了拟南芥AtGlcAT14A编码的一种葡萄糖醛酸基转移酶，它催化将葡萄糖醛酸残基添加到阿拉伯半乳聚糖的β-1,3-和β-1,6-连接的半乳聚糖上（克诺赫等人，2013年）。该基因的敲除突变体导致幼苗下胚轴和根的生长速率提高，表明AtGlcAT14A参与细胞伸长。AtGlcAt14A属于碳水化合物活性酶数据库（CAZy；www.cazy.org）中的GT14家族，其中包括AtGLCAT14A在内，共有11种蛋白质是从拟南芥中分类出来的。在本文中，我们报道了其余拟南芥GT14亚型的酶活性，其分析方法与AtGlcAT14A相同。显然，另外两种拟南芥GT14亚型，At5g15050和At2g37585，也具有将葡萄糖醛酸残基添加到β-1,3-和β-1,6-连接的半乳聚糖上的葡萄糖醛酸基转移酶活性。因此，我们分别将At5g15050和At2g37585命名为AtGlcAT14B和AtGlcAT14C。
