The 1.45 Å resolution structure of the cryptogein–cholesterol complex: a close-up view of a sterol carrier protein (SCP) active site

Cryptogein is a small 10 kDa elicitor produced by the phytoparasitic oomycete Phytophthora cryptogea. The protein also displays a sterol carrier activity. The native protein crystallizes in space group P4₁22, with unit-cell parameters a = b = 46.51, c = 134.9 Å (diffraction limit: 2.1 Å). Its complex with cholesterol crystallizes in space group C222₁, with unit-cell parameters a = 30.96, b = 94.8, c = 65.3 Å and a resolution enhanced to 1.45 Å. The large inner non-specific hydrophobic cavity is able to accommodate a large variety of 3-β-hydroxy sterols. Cryptogein probably acts as a sterol shuttle helping the pathogen to grow and complete its life cycle.