Purification and Functional Characterization of a Soluble Trehalase in Lissorhoptrus oryzophilus (Coleoptera: Curculionidae)

Simple Summary The rice water weevil, Lissorhoptrus oryzophilus Kuschel (Coleoptera: Curculionidae), is indigenous to the United States and has become a significant invasive agricultural pest in China. In this study, we identified and cloned one trehalase gene (LoTRE1) encoding a soluble protein in L. oryzophilus and compared the relative expression levels of LoTRE1 in different tissues. The purified LoTRE1 protein was obtained using a prokaryotic expression system, and its enzymatic properties were explored. Amino acid sequence homology modeling of LoTRE1 and molecular docking between the LoTRE1 protein and substrate trehalose were simulated, which further provided a theoretical basis for revealing the role of LoTRE1 in the degradation mechanism of trehalose. In addition, the LoTRE1 double-stranded RNA (dsRNA) was synthesized in vitro, and its RNAi effect in L. oryzophilus was detected via feeding. The results suggested that LoTRE1 played a vital role in L. oryzophilus development, which could be useful for providing information for insect pest control in the future. Trehalase is the only enzyme known for the irreversible splitting of trehalose and plays a major role in insect growth and development. In this report, we describe a basic study of the trehalase gene fragment encoding a soluble trehalase from Lissorhoptrus oryzophilus (LoTRE1). Sequence alignment and phylogenetic analysis suggested that LoTRE1 was similar to some known insect trehalases and belongs to the Coleoptera trehalase group. Additionally, LoTRE1 was expressed mainly in the fat body. Purified protein was obtained using heterologous expression of LoTRE1 in Escherichia coli, and the recombinant protein exhibited the ability to decompose trehalose. Enzyme-substrate docking indicated the potential involvement of other residues in the catalytic activity, in addition to Asp 333. Moreover, feeding of adults on LoTRE1 dsRNA silenced the transcription of LoTRE1 and thereby reduced the activity of trehalase and increased the trehalose content; it also led to a 12% death rate. This study reveals essential molecular features of trehalase and offers insights into the structural aspects of this enzyme, which might be related to its function. Taken together, the findings demonstrate that LoTRE1 is indispensable for adults of this pest and provide a new target for the control of L. oryzophilus.