Structure of T. castaneum storage protein solved by cryo-electron microscopy

Lucie Valentová¹, Tibor Füzik¹, Pavel Plevka¹

¹Structural virology, Central European Institute of Technology, Masaryk University, Kamenice 5, 625 00, Brno, Czech Republic

Tribolium castaneum is a worldwide pest causing damages of food and stored crops. The beetle became resistant to many types of insecticides. Hexamerin is the most abundant protein in the haemolymph of larvae and pupae of holometabolous insect. It serves as an amino acid source during metamorphosis. Hexamerin was isolated from Tribolium castaneum pupae and purified by ion exchange and gel chromatography. Hexamerin structure was resolved at resolution of 3.28 Å. Hexamerin particle consists of 6 protomers organized in D3 symmetry. Each subunit is N-glycosylated on Asn¹⁸⁷. The glycosylation is located in the cleft between subunits and probably increases the stability of the whole protein. The knowledge of hexamerin structure might shed light on T. castaneum lifecycle and potentially might enable the development of substances for the control of this pest.