PDBsum entry 1uhg

Allergen

PDB id: 1uhg

Contents

Protein chains

383 a.a. *

Ligands

NAG-NAG ×3

SO4 ×7

NAG

Waters ×851

* Residue conservation analysis

PDB id:

1uhg

Name:

Allergen

Title:

Crystal structure of s-ovalbumin at 1.9 angstrom resolution

Structure:

Ovalbumin. Chain: a, b, c, d. Synonym: s-ovalbumin

Source:

Gallus gallus. Chicken. Organism_taxid: 9031. Tissue: egg white

Biol. unit:

Dimer (from PQS)

Resolution:

1.90Å R-factor: 0.196 R-free: 0.247

Authors:

M.Yamasaki,N.Takahashi,M.Hirose

Key ref:

M.Yamasaki et al. (2003). Crystal structure of S-ovalbumin as a non-loop-inserted thermostabilized serpin form. J Biol Chem, 278, 35524-35530. PubMed id: 12840013 DOI: 10.1074/jbc.M305926200

Date:

03-Jul-03 Release date: 22-Jul-03

Protein chains

P01012  (OVAL_CHICK) -  Ovalbumin from Gallus gallus

Seq: 386 a.a.

Struc: 383 a.a.*

* PDB and UniProt seqs differ at 3 residue positions (black crosses)

DOI no: 10.1074/jbc.M305926200

J Biol Chem 278:35524-35530 (2003)

PubMed id: 12840013

Crystal structure of S-ovalbumin as a non-loop-inserted thermostabilized serpin form.

M.Yamasaki, N.Takahashi, M.Hirose.

ABSTRACT

Ovalbumin, a non-inhibitory member of serine proteinase inhibitors (serpin), is transformed into a heat-stabilized form, S-ovalbumin, under elevated pH conditions. The structural mechanism for the S-ovalbumin formation has long been a puzzling question in food science and serpin structural biology. On the basis of the commonly observed serpin thermostabilization by insertion of the reactive center loop into the proximal beta-sheet, the most widely accepted hypothetical model has included partial loop insertion. Here we demonstrate, for the first time, the crystal structure of S-ovalbumin at 1.9-A resolution. This structure unequivocally excludes the partial loop insertion mechanism; the overall structure, including the reactive center loop structure, is almost the same as that of native ovalbumin, except for the significant motion of the preceding loop of strand 1A away from strand 2A. The most striking finding is that Ser-164, Ser-236, and Ser-320 take the d-amino acid residue configuration. These chemical inversions can be directly related to the irreversible and stepwise nature of the transformation from native ovalbumin to S-ovalbumin. As conformational changes of the side chains, significant alternations are found in the values of the chi 1 of Phe-99 and the chi 3 of Met-241. The former conformational change leads to the decreased solvent accessibility of the hydrophobic core around Phe-99, which includes Phe-180 and Phe-378, the highly conserved residues in serpin. This may give a thermodynamic advantage to the structural stability of S-ovalbumin.

Selected figure(s)

Figure 2.
FIG. 2. Structural characteristics of S-ovalbumin. a, the overall main-chain structure of S-ovalbumin. The -helices and -strands are shown in rose and pink, respectively. b, overall structural differences between native ovalbumin and S-ovalbumin. S-ovalbumin structure (pink) is superimposed on native ovalbumin structure (white, Protein Data Bank accession number 1OVA [PDB] ) in a C^a trace. The reactive center loop assumes almost the same conformation as that of native ovalbumin. Marked motion of the preceding loop of strand 1A away from strand 2A (125-128) is displayed with a red arrow. Three observed configurational inversions (Ser-164, Ser-236, and Ser-320) and two conformational transitions (Phe-99 and Met-241) of S-ovalbumin are shown in ball-and-stick form. The figures were produced with molecule D using MOL-SCRIPT (48) and Raster3D (49).

Figure 4.
FIG. 4. Modulation in the hydrophobic interactions around Phe-99. The side-chain conformation around Phe-99 is shown in white for native ovalbumin (Protein Data Bank accession number 1OVA [PDB] ) and in pink for S-ovalbumin. The stereo diagram was produced with molecule D using MOLSCRIPT (48) and Raster3D (49).

The above figures are reprinted by permission from the ASBMB: J Biol Chem (2003, 278, 35524-35530) copyright 2003.

Figures were selected by an automated process.