Intestinal fatty acid-binding protein: the structure and stability of a helix-less variant.


Abstract

The structure of Escherichia coli-derived rat intestinal fatty acid-binding protein (I-FABP) exhibits a beta-clam topology comprised of two five-stranded antiparallel beta-sheets surrounding a large solvent-filled cavity into which the ligand binds. It also contains two alpha-helices that span residues E15-A32 and join beta-strands A and B. This helical domain is conserved in all proteins of this family for which structures have been determined. In order to assess the structural and functional role of the helical domain, we engineered a variant of I-FABP by deleting residues 15-31 and inserting a Ser-Gly linker after residue 14. Circular dichroism measurements indicated that this I-FABP variant, termed delta 17-SG, has a high beta-sheet content similar to that of the wild-type protein. Two-dimensional NMR spectra of delta 17-SG revealed patterns similar to those observed for wild-type I-FABP, except for the selective absence of resonances and through-space interactions assigned to the helical domain. The delta 17-SG variant was less stable to denaturant than wild-type I-FABP, but the folding-unfolding transition was highly cooperative and reversible. Taking into account the lower stability, the refolding kinetics of delta 17-SG were essentially identical to those of wild-type. We conclude that delta 17-SG is a helix-less, essentially all-beta-sheet variant of I-FABP and that the helical domain is not a required element of the beta-clam topology of I-FABP. In addition, the helical domain does not appear to serve as a nucleation site for the refolding process. As shown in the accompanying paper [Cistola, D. P., Kim, K., Rogl, H., & Frieden, C. (1996) Biochemistry 35, 7559-7565], the helices may function to regulate the kinetics and energetics of ligand binding. Study holds ProTherm entries: 5036 Extra Details: additive : EDTA(0.25 mM), antiparallel beta-sheets; solvent-filled cavity; functional role,helical domain; folding-unfolding transition; cooperative

Submission Details

ID: rZygnFM23

Submitter: Connie Wang

Submission Date: April 24, 2018, 8:28 p.m.

Version: 1

Publication Details
Kim K;Cistola DP;Frieden C,Biochemistry (1996) Intestinal fatty acid-binding protein: the structure and stability of a helix-less variant. PMID:8652535
Additional Information

Structure view and single mutant data analysis

Study data

No weblogo for data of varying length.
Colors: D E R H K S T N Q A V I L M F Y W C G P
 

Data Distribution

Studies with similar sequences (approximate matches)

Correlation with other assays (exact sequence matches)


Relevant PDB Entries

Structure ID Release Date Resolution Structure Title
1AEL 1997-04-01 NMR STRUCTURE OF APO INTESTINAL FATTY ACID-BINDING PROTEIN, 20 STRUCTURES
1SA8 2004-06-08 THE NMR STRUCTURE OF A STABLE AND COMPACT ALL-beta-SHEET VARIANT OF INTESTINAL FATTY ACID-BINDING PROTEIN
1T8V 2005-10-04 The NMR structure of d34a i-fabp: implications for the determinants of ligand binding stoichiometry
1A57 1998-05-27 THE THREE-DIMENSIONAL STRUCTURE OF A HELIX-LESS VARIANT OF INTESTINAL FATTY ACID BINDING PROTEIN, NMR, 20 STRUCTURES
1URE 1997-03-12 NMR STRUCTURE OF INTESTINAL FATTY ACID-BINDING PROTEIN COMPLEXED WITH PALMITATE, 20 STRUCTURES
1IFC 1994-01-31 1.19 REFINEMENT OF THE STRUCTURE OF RECOMBINANT RAT INTESTINAL FATTY ACID-BINDING APOPROTEIN AT 1.2 ANGSTROMS RESOLUTION
1ICM 1994-01-31 1.5 ESCHERICHIA COLI-DERIVED RAT INTESTINAL FATTY ACID BINDING PROTEIN WITH BOUND MYRISTATE AT 1.5 A RESOLUTION AND I-FABPARG106-->GLN WITH BOUND OLEATE AT 1.74 A RESOLUTION
3AKN 2011-07-20 1.6 X-ray structure of iFABP from human and rat with bound fluorescent fatty acid analogue
1ICN 1994-01-31 1.74 ESCHERICHIA COLI-DERIVED RAT INTESTINAL FATTY ACID BINDING PROTEIN WITH BOUND MYRISTATE AT 1.5 A RESOLUTION AND I-FABPARG106-->GLN WITH BOUND OLEATE AT 1.74 A RESOLUTION
1IFB 1992-01-15 1.96 REFINED APOPROTEIN STRUCTURE OF RAT INTESTINAL FATTY ACID BINDING PROTEIN PRODUCED IN ESCHERICHIA COLI
2IFB 1992-01-15 2.0 CRYSTAL STRUCTURE OF RAT INTESTINAL FATTY-ACID-BINDING PROTEIN. REFINEMENT AND ANALYSIS OF THE ESCHERICHIA COLI-DRIVED PROTEIN WITH BOUND PALMITATE
1DC9 2000-03-20 2.1 PROPERTIES AND CRYSTAL STRUCTURE OF A BETA-BARREL FOLDING MUTANT, V60N INTESTINAL FATTY ACID BINDING PROTEIN (IFABP)

Relevant UniProtKB Entries

Percent Identity Matching Chains Protein Accession Entry Name
97.0 Fatty acid-binding protein, brain P51880 FABP7_MOUSE
100.0 Fatty acid-binding protein, brain P55051 FABP7_RAT
92.4 Fatty acid-binding protein, intestinal P55050 FABPI_MOUSE
100.0 Fatty acid-binding protein, intestinal P02693 FABPI_RAT