PDBsum entry 1a57

Fatty acid-binding

PDB id: 1a57

Contents

Protein chain

116 a.a. *

* Residue conservation analysis

PDB id:

1a57

Name:

Fatty acid-binding

Title:

The three-dimensional structure of a helix-less variant of intestinal fatty acid binding protein, nmr, 20 structures

Structure:

Intestinal fatty acid-binding protein. Chain: a. Synonym: delta17sg, ifabp, i-fabp. Engineered: yes. Other_details: helix-less, complexed with palmitate

Source:

Rattus norvegicus. Norway rat. Organism_taxid: 10116. Cell: small intestinal enterocyte. Cellular_location: cytoplasm. Expressed in: escherichia coli str. K-12 substr. Mg1655. Expression_system_taxid: 511145. Other_details: see remark 1, reference 3

NMR struc:

20 models

Authors:

R.A.Steele,D.A.Emmert,J.Kao,M.E.Hodsdon,C.Frieden,D.P.Cistola

Key ref:

R.A.Steele et al. (1998). The three-dimensional structure of a helix-less variant of intestinal fatty acid-binding protein. Protein Sci, 7, 1332-1339. PubMed id: 9655337 DOI: 10.1002/pro.5560070609

Date:

20-Feb-98 Release date: 27-May-98

Protein chain

P02693  (FABPI_RAT) -  Fatty acid-binding protein, intestinal from Rattus norvegicus

Seq: 132 a.a.

Struc: 116 a.a.*

* PDB and UniProt seqs differ at 1 residue position (black cross)

Enzyme reactions

• Enzyme class: E.C.?

DOI no: 10.1002/pro.5560070609

Protein Sci 7:1332-1339 (1998)

PubMed id: 9655337

The three-dimensional structure of a helix-less variant of intestinal fatty acid-binding protein.

R.A.Steele, D.A.Emmert, J.Kao, M.E.Hodsdon, C.Frieden, D.P.Cistola.

ABSTRACT

Intestinal 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.

Selected figure(s)

Figure 1.
Fig. 1. Solution-state NMR stucture f wild-type at intestinalfatty acid binding rotein complexed withpalmitate (Hodsdon et al., 1996). The X-ray crystal structure f this complex is identical (Sacchettini et al.. 1989). The arrows indicate residues at th beginning andend of he deletion site in the A17-SG variant. The boundpalmitate is shown in CP formwith its carboxy terminusbehindstrand D. This figure was created with MOMOL (Koradi et al.. 1996).

Figure 6.
Fig. 6. Solvent-accessiblesurfacerepresentations of wld-typendheli-less I-FABP NMR structures.The view is romdirctlyabve the helices and proposed portal entrance.Thesurface is colored by residuetype; P-sheetresidues:magenta. helical residues: all otherresidues.Tisfigure was made with the program MOLMOL v2.4. u hg Lee and Richardscontactsurface(Lee & Richards. 197 I ) wlth asolventmlecule of radius 1.3 A. The arrow indicates the deletion-site loop.

The above figures are reprinted from an Open Access publication published by the Protein Society: Protein Sci (1998, 7, 1332-1339) copyright 1998.

Figures were selected by an automated process.