BACKGROUND The chitin biosynthesis pathway starts with trehalose in insects and the main functions of trehalases are hydrolysis of trehalose to glucose. Although insects possess two types, soluble trehalase (Tre-1) and membrane-bound trehalase (Tre-2), very little is known about Tre-2 and the difference in function between Tre-1 and Tre-2. RESULTS To gain an insight into trehalase functions in insects, we investigated a putative membrane-bound trehalase from Spodoptera exigua (SeTre-2) cloned from the fat body. The deduced amino acid sequence of SeTre-2 contains 645 residues and has a predicted molecular weight of approximately 74 kDa and pI of 6.01. Alignment of SeTre-2 with other insect trehalases showed that it contains two trehalase signature motifs and a putative transmembrane domain, which is an important characteristic of Tre-2. Comparison of the genomic DNA and cDNA sequences demonstrated that SeTre-2 comprises 13 exons and 12 introns. Southern blot analysis revealed that S. exigua has two trehalase genes and that SeTre-2 is a single-copy gene. Northern blot analyses showed that the SeTre-2 transcript is expressed not only in the midgut, as previously reported for Bombyx mori, but also in the fat body and Malpighian tubules, although expression patterns differed between the midgut and fat body. SeTre-2 transcripts were detected in the midgut of feeding stage larvae, but not in pupae, whereas SeTre-2 mRNA was detected in the fat body of fifth instar larvae and pupae. CONCLUSION These findings provide new data on the tissue distribution, expression patterns and potential function of membrane-bound trehalase. The results suggest that the SeTre-2 gene may have different functions in the midgut and fat body.

中文翻译：

---

来自甜菜夜蛾的膜结合海藻糖酶的表征和表达模式。

背景技术昆虫的甲壳素生物合成途径始于海藻糖，海藻糖酶的主要功能是将海藻糖水解为葡萄糖。尽管昆虫具有两种类型，可溶性海藻糖酶 (Tre-1) 和膜结合海藻糖酶 (Tre-2)，但人们对 Tre-2 以及 Tre-1 和 Tre-2 之间的功能差异知之甚少。结果 为了深入了解昆虫中的海藻糖酶功能，我们研究了从脂肪体克隆的来自甜菜夜蛾 (SeTre-2) 的推定膜结合海藻糖酶。SeTre-2 的推导氨基酸序列包含 645 个残基，预测分子量约为 74 kDa，pI 为 6.01。SeTre-2 与其他昆虫海藻糖酶的比对表明，它包含两个海藻糖酶特征基序和一个推定的跨膜结构域，这是 Tre-2 的一个重要特征。基因组 DNA 和 cDNA 序列的比较表明，SeTre-2 包含 13 个外显子和 12 个内含子。Southern印迹分析显示S. exigua具有两个海藻糖酶基因并且SeTre-2是单拷贝基因。Northern印迹分析表明，SeTre-2转录物不仅在中肠中表达，如先前对家蚕的报道，而且还在脂肪体和马氏小管中表达，尽管中肠和脂肪体之间的表达模式不同。在摄食期幼虫的中肠中检测到 SeTre-2 转录本，但在蛹中未检测到，而在五龄幼虫和蛹的脂肪体中检测到 SeTre-2 mRNA。结论这些发现提供了关于膜结合海藻糖酶的组织分布、表达模式和潜在功能的新数据。