The climate crisis places enormous pressure on beneficial pollinators, affects food supply chains, amplifies vector-borne diseases, and costs the global economy to tune of billions annually. Insecticidal pore-forming proteins (PFPs) represent crucial tools to battle this enormous problem. PFPs have roles in pest control strategies, contributing to public health initiatives and food security. For instance, PFPs derived from Bacillus thuringiensis (Bt) strains are widely employed in crops (e.g. cotton, corn, eggplant, etc) to eliminate pests, thereby reducing food loss in developing and developed nations. Furthermore, PFPs reduce agricultural reliance on chemical insecticides that decimate beneficial insect populations. Similarly, PFPs have been successfully used to control mosquito populations, again providing a tool to mitigate vector-borne diseases such as malaria, which remains the single leading cause of preventable illness and death worldwide. However, the market is dominated by a dangerously small subset of PFPs and emerging resistance jeopardises global food security and disease-control initiatives. Secondly, despite their proven utility, there is limited understanding of the exact molecular mechanisms that underlying many PFPs. This includes knowledge of target insects; interactions with the target membranes, receptors, and resistance-mechanisms; and the activation triggers, process of oligomerisation, pore formation and death-mechanism.
Our studies have revealed enormous variation between and within classes of PFP. By applying an integrative methodology that leverages cryo-electron microscopy, crystallography, live-insect assays, and biophysical methods, we report the mechanisms of both emerging and established PFPs. We provide three exemplars. Coprinolysin is a larvicidal fungal-derived protein, which targets mosquitoes and nematodes. We describe a structure-function analysis and discover a unique packaging intermediate. The second study describes the structure and mechanism of receptor recognition by the WHO-approved binary protein Tpp1/Tpp2. Tpp1/Tpp2 targets the mosquito midgut receptor Cqm1. Finally, we describe the structure of Vpb4, known to target Western Corn Rootworm that causes over US $1 billion in crop damage annually.
Collectively, this work enhances our understanding of PFPs as insect control measures paving the way for targeted and sustainable pest control solutions with broad implications for both public health, agriculture and implications for tackling the climate crisis.