From gene to function: GABA receptor-associated protein (GABARAP) interacts with and potentiates the GABA receptor (RDL) in Megalurothrips usitatus (Bagnall) (Thysanoptera: Thripidae).

The GABA receptor-associated protein (GABARAP), a member of the autophagy-related protein 8 (ATG8) family, regulates autophagy and GABAA receptor trafficking in mammals, yet its functional role in insects remains completely unexplored. The bean flower thrips, Megalurothrips usitatus, is a globally invasive pest whose control is increasingly challenged by widespread insecticide resistance. Understanding novel regulatory mechanisms in its nervous system, particularly those involving the insecticidal target GABA receptor (RDL), is therefore crucial. Spatiotemporal expression profiling revealed that GABARAP was predominantly expressed in the pseudopupa stage and in head tissues of M. usitatus. Its transcript level showed a significant positive correlation with the RDL expression across geographically distinct populations, and RNA interference (RNAi) GABARAP knockdown led to a concurrent reduction in RDL expression. Functional electrophysiology in Xenopus oocytes demonstrated that GABARAP and RDL co-expression enhanced the RDL sensitivity to GABA, lowering the EC₅₀ from 35.09 μM to 27.27 μM and increasing the maximal current response. Computational analyses confirmed the interaction: molecular docking predicted a stable, high-affinity GABARAP-RDL complex involving key residues (such as GABARAP GLU-101 and RDL ARG-411), and molecular dynamics simulations demonstrated its structural stability. MM/GBSA energy decomposition identified van der Waals forces as the primary drivers of complex formation. By providing the first evidence in insects that GABARAP directly binds to and potentiates the RDL receptor, this study establishes GABARAP as a positive regulator of inhibitory neurotransmission, thereby revealing a novel regulatory mechanism for insect GABA receptors. Therefore, the GABARAP-RDL interface thus represents a potential target for novel pest-control strategies.