title: A thermoacidophile-specific protein family, DUF3211, functions as a fatty acid carrier with novel binding mode.
abstract: STK_08120 is a member of the thermoacidophile-specific DUF3211 protein family from Sulfolobus tokodaii strain 7. Its molecular function remains obscure, and sequence similarities for obtaining functional remarks are not available. In this study, the crystal structure of STK_08120 was determined at 1.79-Å resolution to predict its probable function using structure similarity searches. The structure adopts an α/β structure of a helix-grip fold, which is found in the START domain proteins with cavities for hydrophobic substrates or ligands. The detailed structural features implied that fatty acids are the primary ligand candidates for STK_08120, and binding assays revealed that the protein bound long-chain saturated fatty acids (>C14) and their trans-unsaturated types with an affinity equal to that for major fatty acid binding proteins in mammals and plants. Moreover, the structure of an STK_08120-myristic acid complex revealed a unique binding mode among fatty acid binding proteins. These results suggest that the thermoacidophile-specific protein family DUF3211 functions as a fatty acid carrier with a novel binding mode.
authors.affiliation: Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo, Japan.
authors.forename: Takuya
authors.initials: T
authors.lastname: Miyakawa
authors.forename: Yoriko
authors.initials: Y
authors.lastname: Sawano
authors.forename: Ken-ichi
authors.initials: K
authors.lastname: Miyazono
authors.forename: Yumiko
authors.initials: Y
authors.lastname: Miyauchi
authors.forename: Ken-ichi
authors.initials: K
authors.lastname: Hatano
authors.forename: Masaru
authors.initials: M
authors.lastname: Tanokura
mesh_terms: D002352:Carrier Proteins / Q000737:chemistry* / Q000378:metabolism*; D018360:Crystallography, X-Ray; D005227:Fatty Acids / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D011485:Protein Binding; D011487:Protein Conformation; D016944:Sulfolobus / Q000737:chemistry* / Q000378:metabolism*; D013696:Temperature
chemical_list: D002352:Carrier Proteins; D005227:Fatty Acids