The X-Ray structure of Sterol Carrier Protein 2 from Yarrowia lipolytica and the evolutionary conservation of a large, non-specific lipid-binding cavity

PEREZ DE BERTI, FEDERICO J.; CAPALDI, STEFANO; FERREYRA, RAUL G.; BURGARDT, NOELIA I.; KLINKED, SEBASTIÁN; MÓNACO, HUGO L.; ERMÁCORA, MARIO R.

Journal of Structural and Functional Genomics

Springer Netherlands

Lugar: Dordrecht; Año: 2013 vol. 14 p. 145 - 153

1345-711X

Sterol carrier protein 2 (SCP2), a small intracellular domain present in all forms of life, binds with high affinity a broad spectrum of lipids. Due to its involvement in the metabolism of long-chain fatty acids and cholesterol uptake, it has been the focus of intense research in mammals and insects; much less characterized are SCP2 from other eukaryotic cells and microorganisms. We report the X-ray structure of Yarrowia lipolytica SCP2 (YLSCP2) at 2.2 A resolution in complex with palmitic acid. This is the first fungal SCP2 structure solved, and it consists of a five-stranded beta-sheet covered on the internal face by a layer of five alfa-helices. The overall fold is conserved among the SCP2 family, however, YLSCP2 is most similar to the SCP2 domain of human MFE-2, a bifunctional enzyme acting on peroxisomal beta-oxidation. We identified the common structural elements defining the shape and volume of the large binding cavity in all species characterized. Moreover, we found that the cavity of the SCP2 domains is distinctly formed by carbon atoms, containing neither organized water nor rigid polar interactions with the ligand. These features are in contrast with those of fatty acid binding proteins, whose internal cavities are more polar and contain bound water. The results will help to design experiments to unveil the SCP2 function in very different cellular contexts and metabolic conditions.