Wang Jia, Fan Huan, Li Ying, Zhang Tong-Fang, Liu Ying-Hong
College of Plant Protection, Southwest University, Chongqing, China.
College of Food Science, Southwest University, Chongqing, China.
Insect Sci. 2022 Dec;29(6):1643-1658. doi: 10.1111/1744-7917.13010. Epub 2022 Feb 17.
Trehalose is the principal sugar circulating in the hemolymph of insects, and trehalose synthesis is catalyzed by trehalose-6-phosphate synthase (TPS) and trehalose-6-phosphate phosphatase (TPP). Insect TPS is a fused enzyme containing both TPS domain and TPP domain. Thus, many insects do not possess TPP genes as TPSs have replaced the function of TPPs. However, TPPs are widely distributed across the dipteran insects, while the roles they play remain largely unknown. In this study, 3 TPP genes from notorious dipteran pest Bactrocera minax (BmiTPPB, BmiTPPC1, and BmiTPPC2) were identified and characterized. The different temporal-spatial expression patterns of 3 BmiTPPs implied that they exert different functions in B. minax. Recombinant BmiTPPs were heterologously expressed in yeast cells, and all purified proteins exhibited enzymatic activities, despite the remarkable disparity in performance between BmiTPPB and BmiTPPCs. RNA interference revealed that all BmiTPPs were successfully downregulated after double-stranded RNA injection, leading to decreased trehalose content and increased glucose content. Also, suppression of BmiTPPs significantly affected expression of downstream genes and increased the mortality and malformation rate. Collectively, these results indicated that all 3 BmiTPPs in B. minax are involved in trehalose synthesis and metamorphosis. Thus, these genes could be evaluated as insecticidal targets for managing B. minax, and even for other dipteran pests.
海藻糖是昆虫血淋巴中循环的主要糖类，海藻糖的合成由海藻糖-6-磷酸合酶（TPS）和海藻糖-6-磷酸磷酸酶（TPP）催化。昆虫TPS是一种融合酶，包含TPS结构域和TPP结构域。因此，许多昆虫不具有TPP基因，因为TPS已经取代了TPP的功能。然而，TPP广泛分布于双翅目昆虫中，但其所起的作用仍 largely未知。在本研究中，从臭名昭著的双翅目害虫橘小实蝇中鉴定并表征了3个TPP基因（BmiTPPB、BmiTPPC1和BmiTPPC2）。3个BmiTPP的不同时空表达模式表明它们在橘小实蝇中发挥不同功能。重组BmiTPP在酵母细胞中异源表达，尽管BmiTPPB和BmiTPPC之间的性能存在显著差异，但所有纯化蛋白均表现出酶活性。RNA干扰显示，注射双链RNA后所有BmiTPP均成功下调，导致海藻糖含量降低和葡萄糖含量增加。此外，抑制BmiTPP显著影响下游基因的表达，并增加死亡率和畸形率。总体而言，这些结果表明橘小实蝇中的所有3个BmiTPP都参与海藻糖合成和变态。因此，这些基因可作为管理橘小实蝇甚至其他双翅目害虫的杀虫靶标进行评估。
