1a57
From Proteopedia
THE THREE-DIMENSIONAL STRUCTURE OF A HELIX-LESS VARIANT OF INTESTINAL FATTY ACID BINDING PROTEIN, NMR, 20 STRUCTURES
Structural highlights
FunctionFABPI_RAT FABP are thought to play a role in the intracellular transport of long-chain fatty acids and their acyl-CoA esters. FABP2 is probably involved in triglyceride-rich lipoprotein synthesis. Binds saturated long-chain fatty acids with a high affinity, but binds with a lower affinity to unsaturated long-chain fatty acids. FABP2 may also help maintain energy homeostasis by functioning as a lipid sensor (By similarity). Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedIntestinal fatty acid-binding protein (I-FABP) is a cytosolic 15.1-kDa protein that appears to function in the intracellular transport and metabolic trafficking of fatty acids. It binds a single molecule of long-chain fatty acid in an enclosed cavity surrounded by two five-stranded antiparallel beta-sheets and a helix-turn-helix domain. To investigate the role of the helical domain, we engineered a variant of I-FABP by deleting 17 contiguous residues and inserting a Ser-Gly linker (Kim K et al., 1996, Biochemistry 35:7553-7558). This variant, termed delta17-SG, was remarkably stable, exhibited a high beta-sheet content and was able to bind fatty acids with some features characteristic of the wild-type protein. In the present study, we determined the structure of the delta17-SG/palmitate complex at atomic resolution using triple-resonance 3D NMR methods. Sequence-specific 1H, 13C, and 15N resonance assignments were established at pH 7.2 and 25 degrees C and used to define the consensus 1H/13C chemical shift-derived secondary structure. Subsequently, an iterative protocol was used to identify 2,544 NOE-derived interproton distance restraints and to calculate its tertiary structure using a unique distance geometry/simulated annealing algorithm. In spite of the sizable deletion, the delta17-SG structure exhibits a backbone conformation that is nearly superimposable with the beta-sheet domain of the wild-type protein. The selective deletion of the alpha-helical domain creates a very large opening that connects the interior ligand-binding cavity with exterior solvent. Unlike wild-type I-FABP, fatty acid dissociation from delta17-SG is structurally and kinetically unimpeded, and a protein conformational transition is not required. The delta17-SG variant of I-FABP is the only wild-type or engineered member of the intracellular lipid-binding protein family whose structure lacks alpha-helices. Thus, delta17-SG I-FABP constitutes a unique model system for investigating the role of the helical domain in ligand-protein recognition, protein stability and folding, lipid transfer mechanisms, and cellular function. The three-dimensional structure of a helix-less variant of intestinal fatty acid-binding protein.,Steele RA, Emmert DA, Kao J, Hodsdon ME, Frieden C, Cistola DP Protein Sci. 1998 Jun;7(6):1332-9. PMID:9655337[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. Loading citation details.. Citations No citations found See AlsoReferences
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