Three‐dimensional structure of fatty‐acid‐binding protein from bovine heart

Open Access
Publisher Website
Google Scholar
Abstract
The complex of fatty-acid-binding protein (FABP) from bovine heart (cFABP, pI 4.9) with endogenous lipid was crystallized in the presence of ammonium sulfate as precipitant. The needle-shaped crystals belong to the monoclinic space group C2, with unit-cell constants a= 5.262(6) nm, b= 7.631(8) nm, c= 3.945(5) nm and β= 94.47(9)°. A native data set to 0.35 nm resolution was collected using synchrotron radiation and film methods. An initial model for the three-dimensional structure of the protein was constructed based on the crystal structure of the related bovine P2 myelin protein [Jones, T. A., Bergfors, T., Sedzik, J. & Unge, T. (1988) EMBO J. 7, 1597–1604] to which the amino acid sequence of bovine cFABP was adapted. Energy minimizations were carried out under different conditions using both an all-atom and a united-atom force field. The optimized models were used to determine the crystal structure of cFABP by molecular-replacement techniques. The structure was refined by simulated annealing to R= 0.267. As the bound lipid is heterogeneous, it could not be located in the electron-density map and/or the attained resolution was not sufficient. Bovine cFABP is composed of ten antiparallel β strands forming a β barrel, and by two α helices. The structural features are similar to those of other members of the superfamily of hydrophobic molecule transporters.