Crystal structure of rat intestinal fatty-acid-binding protein Refinement and analysis of the Escherichia coli-derived protein with bound palmitate | Academic Article individual record

Rat intestinal fatty-acid-binding protein (I-FABP) is a small (15,124 Mr) cytoplasmic polypeptide that binds long-chain fatty acids in a non-covalent fashion. I-FABP is a member of a family of intracellular binding proteins that are thought to participate in the uptake, transport and/or metabolic targeting of hydrophobic ligands. The crystal structure of Escherichia coli-derived rat I-FABP with a single molecule of bound palmitate has been refined to 2 A resolution using a combination of least-squares methods, energy refinement and molecular dynamics. The combined methods resulted in a model with a crystallographic R-factor of 17.8% (7775 reflections, sigma greater than 2.0), root-mean-square bond length deviation of 0.009 A and root-mean-square bond angle deviation of 2.85 degrees. I-FABP contains ten antiparallel beta-strands organized into two approximately orthogonal, beta-sheets. The hydrocarbon tail of its single C16:0 ligand is present in a well-ordered, distinctively bent conformation. The carboxylate group of the fatty acid is located in the interior of I-FABP and forms a unique \"quintet\" of electrostatic interactions involving Arg106; Gln 115, and two solvent molecules. The hydrocarbon tail is bent with a slight left-handed helical twist from the carboxylate group to C-16. The bent methylene chain resides in a \"cradle\" formed by the side-chains of hydrophobic, mainly aromatic, amino acid residues. The refined molecular model of holo-I-FABP suggests several potential locations for entry and exiting of the fatty acid.

author list (cited authors)
Sacchettini, J. C., Gordon, J. I., & Banaszak, L. J.
publication date
Elsevier bv Publisher
published in
  • Protein Conformation
  • Palmitic Acids
  • Models, Molecular
  • Intestines
  • Animals
  • Escherichia Coli
  • Hydrogen Bonding
  • Intestinal Mucosa
  • Fatty Acid-binding Proteins
  • Molecular Sequence Data
  • Carrier Proteins
  • Neoplasm Proteins
  • Ligands
  • Fatty Acids
  • Rats
  • Temperature
  • Palmitates
  • X-Ray Diffraction
  • Amino Acid Sequence
  • Fatty Acid-binding Protein 7
  • Nerve Tissue Proteins
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