Crystal structures of the sweet-tasting protein honey truffle active component from Mattirolomyces terfezioides

Crystal structures of honey truffle active component (HT-AC) originally derived from the fungus Mattirolomyces terfezioides are reported for the first time. HT-AC is a 13 kDa protein and is one of a small class of unrelated proteins that interact with an allosteric site on the human T1R2/R3 sweet taste receptor. These proteins can be used as sweeteners, and result in sweet taste perception at lower concentrations than sugar (the orthosteric receptor target) or many other high-intensity small-molecule sweeteners. Orthorhombic (space group P 2 1 2 1 2 1 ) and monoclinic (space group P 2 1 ) crystal structures of HT-AC are reported at resolutions ranging from 1.23 to 1.70 Å.