College of Life Sciences, Ritsumeikan University, Kusatsu, Shiga, 525-8577, Japan.
Ritsumeikan Global Innovation Research Organization, Ritsumeikan University, Kusatsu, Shiga, 525-8577, Japan.
Plant Physiol Biochem. 2019 Sep;142:173-178. doi: 10.1016/j.plaphy.2019.07.008. Epub 2019 Jul 4.
Rhamnogalacturonan I (RG-I), one of the pectic components of the plant cell wall, is composed of a backbone of repeating disaccharide units of rhamnose and galacturonic acid, and side chains, such as galactans, arabinans, and arabinogalactans. The activity of RG-I galactosyltransferase, which transfers galactosyl residues to rhamnosyl residues in the RG-I backbone, has not been detected until now. Here, we detected galactosyltransferase activity in azuki bean epicotyls using fluorogenic RG-I oligosaccharide acceptors. This enzyme prefers oligosaccharides with a degree of polymerization more than 9. The enzyme activity was detected in the Golgi apparatus, which is the site of pectin synthesis. In vitro hyperactivation of this enzyme was also observed. Moreover, enzyme activity was increased up to 40-fold in the presence of cationic surfactants or polyelectrolytes.
鼠李半乳糖醛酸聚糖 I（RG-I）是植物细胞壁中果胶的成分之一，由鼠李糖和半乳糖醛酸重复二糖单元组成的主链和半乳糖、阿拉伯聚糖和阿拉伯半乳聚糖等侧链组成。到目前为止，还没有检测到 RG-I 半乳糖基转移酶的活性，该酶将半乳糖基残基转移到 RG-I 主链中的鼠李糖基残基上。在这里，我们使用荧光 RG-I 寡糖受体检测到了赤豆下胚轴中的半乳糖基转移酶活性。该酶优先作用于聚合度大于 9 的寡糖。该酶活性在高尔基器中被检测到，高尔基器是果胶合成的部位。体外也观察到该酶的过度激活。此外，在阳离子表面活性剂或聚电解质存在的情况下，酶活性增加了 40 倍。
