066 Crystal structure of the Rhagium Inquisitor antifreeze protein

Some insects use antifreeze proteins to overwinter. The structure-function relationships and mechanism of action of these proteins are not well understood. We report the crystal structure of an antifreeze protein from the longhorn beetle Rhagium inquisitor , determined at 1.15-A resolution using ab initio direct methods. The structure is the largest determined ab initio without heavy atoms, and reveals a compressed β -solenoid fold in which the top and bottom sheets are held together by a silk-like interdigitation of short side chains. The crystal structure shows the presence of ice-like waters that match several planes of hexagonal ice. Source of funding: NIH grant P01 GM022778. Conflict of interest: None declared. wuyi.meng@yale.edu