Expression and purification of snustorr snarlik protein from Plutella xylostella

Snustorr snarlik (Snsl) is a type of extracellular protein essential for insect cuticle formation and insect survival, but is absent in mammals, making it a potential selective target for pest control. Here, we successfully expressed and purified the Snsl protein of Plutella xylostella in Escherichia coli. Two truncated forms of Snsl protein, Snsl 16-119 and Snsl 16-159, were expressed as a maltose-binding protein (MBP) fusion protein and purified to a purity above 90% after a five-step purification protocol. Snsl 16-119, forming stable monomer in solution, was crystallized, and the crystal was diffracted to a resolution of ∼10 Å. Snsl 16-159, forming an equilibrium between monomer and octamer in solution, was shown to form rod-shaped particles on negative staining electron-microscopy images. Our results lay a foundation for the determination of the structure of Snsl, which would improve our understanding of the molecular mechanism of cuticle formation and related pesticide resistance and provide a template for structure-based insecticide design.