Molecular characterization of a voltage-gated calcium channel and its potential role in the acaricidal action of scopoletin against Tetranychus cinnabarinus

The carmine spider mite, Tetranychus cinnabarinus (Boisduval), is a polyphagous agricultural pest with an extensive host plant range. Scopoletin is a promising acaricidal compound whose acaricidal mechanism may occur by disrupting intracellular Ca²⁺ homeostasis and calcium signaling pathways. However, the underlying mechanism of scopoletin for specific target locations of T. cinnabarinus remains unclear. In this study, a full-length cDNA of the L-type voltage-gated calcium channel (TcLTCC) subunit gene from T. cinnabarinus was cloned and characterized. The expression pattern of the TcLTCC gene in all developmental stages of T. cinnabarinus was analyzed. The gene was highly expressed in larval and nymphal stages and was significantly upregulated after treatment with scopoletin. Knocking down the TcLTCC transcript reduced the sensitivity of T. cinnabarinus to scopoletin. Homology modeling and molecular docking were also conducted. The interaction between scopoletin and TcLTCC showed that scopoletin inserted into the cavity bound to the site of the TcLTCC protein by the driving force of hydrogen bonding. This study provides insights into the mechanism by which scopoletin interacts with TcLTCC. Results can improve the understanding of the toxicity of scopoletin to T. cinnabarinus and provide valuable information for the design of new LTCC inhibitors.

Keywords: Calcium channel; Interaction mechanism; Molecular docking; RNAi; Scopoletin; TcLTCC; Tetranychus cinnabarinus.