Cyt1Aa

Cyt1Aa is a protein produced by certain strains of the bacterium *Bacillus thuringiensis*. It belongs to a class of proteins known as Cry proteins, which are often referred to as delta-endotoxins. These proteins are synthesized by the bacterium as crystalline inclusions during its sporulation phase. When ingested by susceptible insect larvae, these crystals are solubilized in the insect's gut. The solubilized Cyt1Aa is then processed by insect proteases into smaller active fragments. These active fragments interact with specific receptors on the insect midgut epithelial cells, leading to pore formation. This disruption of the midgut epithelium causes cell lysis, ultimately leading to the death of the insect.

Cyt1Aa is known for its insecticidal activity, particularly against a range of dipteran insects, including mosquitoes and blackflies. Unlike some other Cry proteins that are specific to lepidopteran or coleopteran pests, Cyt1Aa exhibits a broader spectrum of activity, though its primary targets are in the order Diptera. In addition to its direct insecticidal properties, Cyt1Aa has also been studied for its synergistic effects when used in combination with other *Bacillus thuringiensis* toxins. This means that the combination of Cyt1Aa with other toxins can be more effective at killing insects than either toxin alone. This synergistic activity has implications for developing more potent and resistance-breaking biopesticides. The study of Cyt1Aa contributes to our understanding of bacterial protein toxins and their potential applications in pest management.