2ju8
Solution-State Structures of Oleate-Liganded LFABP, Major Form of 1:2 Protein-Ligand Complex
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OverviewOverview
Rat liver fatty acid-binding protein (LFABP) is distinctive among, intracellular lipid-binding proteins (iLBPs): more than one molecule of, long-chain fatty acid and a variety of diverse ligands can be bound within, its large cavity, and in vitro lipid transfer to model membranes follows a, mechanism that is diffusion-controlled rather than mediated by, protein-membrane collisions. Because the apoprotein has proven resistant, to crystallization, nuclear magnetic resonance spectroscopy offers a, unique route to functionally informative comparisons of molecular, structure and dynamics for LFABP in free (apo) and liganded (holo) forms., We report herein the solution-state structures determined for apo-LFABP at, pH 6.0 and for holoprotein liganded to two oleates at pH 7.0, as well as, the structure of the complex including locations of the ligands. 1H, 13C, and 15N resonance assignments revealed very similar types and locations of, secondary structural elements for apo- and holo-LFABP as judged from, chemical shift indices. The solution-state tertiary structures of the, proteins were derived with the CNS/ARIA computational protocol, using, distance and angular restraints based on 1H-1H nuclear Overhauser effects, (NOEs), hydrogen-bonding networks, 3J(HNHA) coupling constants, intermolecular NOEs, and residual dipolar (NH) couplings. The holo-LFABP, solution-state conformation is in substantial agreement with a previously, reported X-ray structure [Thompson, J., Winter, N., Terwey, D., Bratt, J., and Banaszak, L. (1997) The crystal structure of the liver fatty, acid-binding protein. A complex with two bound oleates, J. Biol. Chem., 272, 7140-7150], including the typical beta-barrel capped by a, helix-turn-helix portal. In the solution state, the internally bound, oleate has the expected U-shaped conformation and is tethered, electrostatically, but the extended portal ligand can adopt a range of, conformations based on the computationally refined structures, in contrast, to the single conformation observed in the crystal structure. The, apo-LFABP also has a well-defined beta-barrel structural motif typical of, other members of the iLBP protein family, but the portal region that is, thought to facilitate ligand entry and exit exhibits conformational, variability and an unusual "open cap" orientation with respect to the, barrel. These structural results allow us to propose a model in which, ligand binding to LFABP occurs through conformational fluctuations that, adjust the helix-turn-helix motif to open or close the top of the, beta-barrel, and solvent accessibility to the protein cavity favors, diffusion-controlled ligand transport.
About this StructureAbout this Structure
2JU8 is a Single protein structure of sequence from Rattus norvegicus with as ligand. Full crystallographic information is available from OCA.
ReferenceReference
Solution-State Molecular Structure of Apo and Oleate-Liganded Liver Fatty Acid-Binding Protein., He Y, Yang X, Wang H, Estephan R, Francis F, Kodukula S, Storch J, Stark RE, Biochemistry. 2007 Nov 6;46(44):12543-12556. Epub 2007 Oct 10. PMID:17927211
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