International Center for Biotechnology, Osaka University, 2-1 Yamada-oka, Suita-shi, Osaka, 565-0871, Japan.
International Center for Biotechnology, Osaka University, 2-1 Yamada-oka, Suita-shi, Osaka, 565-0871, Japan.
Biochem Biophys Res Commun. 2020 Aug 20;529(2):404-410. doi: 10.1016/j.bbrc.2020.05.065. Epub 2020 Jul 1.
N-Acetylglucosaminyltransferase II (GNTII), which catalyzes the transfer of N-acetylglucosamine to N-glycans, plays an essential role in the biosynthesis of branched and complex-type N-glycans. Some characteristics of the GNTIIs from various species have been identified, but not all features have been revealed because some insects have GNTII redundancies due to the possession of splicing variants. In this study, we focused on four splicing variants of silkworm Bombyx mori GNTII (BmGNTII) that differ only in the absence or presence of Exon 2, Exon 9 or both, and we characterized the spatiotemporal transcript levels and enzymatic properties of each. Two of the splicing variants, BmGNTII-B and BmGNTII-D, lack Exon 9, and were expressed more highly in silk glands than any other organs. With respect to the enzymatic properties, optimal temperature and pH were similar among the recombinant BmGNTIIs, but the specific activities and temperature stabilities differed according to the presence or absence of Exon 9 in the splicing variants. These results demonstrate that the B. mori genome encodes splicing variants of GNTII with different enzymatic properties.
N-乙酰氨基葡萄糖基转移酶 II（GNTII），它催化 N-乙酰葡萄糖胺向 N-聚糖的转移，在分支和复杂型 N-聚糖的生物合成中发挥着重要作用。已经鉴定出来自各种物种的 GNTII 的一些特征，但并非所有特征都已揭示出来，因为由于存在剪接变体，一些昆虫具有 GNTII 冗余。在这项研究中，我们专注于蚕 Bombyx mori GNTII（BmGNTII）的四个剪接变体，它们仅在是否存在外显子 2、外显子 9 或两者上有所不同，并且我们对每个变体的时空转录水平和酶特性进行了表征。两种剪接变体 BmGNTII-B 和 BmGNTII-D 缺失外显子 9，在丝腺中的表达高于任何其他器官。就酶特性而言，重组 BmGNTII 之间的最适温度和 pH 相似，但根据剪接变体中外显子 9 的存在与否，特异性活性和温度稳定性有所不同。这些结果表明，B. mori 基因组编码具有不同酶特性的 GNTII 剪接变体。
