PDBsum entry 1jti

Allergen

PDB id: 1jti

Contents

Protein chains

381 a.a. *

Waters ×111

* Residue conservation analysis

PDB id:

1jti

Name:

Allergen

Title:

Loop-inserted structure of p1-p1' cleaved ovalbumin mutant r339t

Structure:

Ovalbumin. Chain: a, b. Engineered: yes. Mutation: yes

Source:

Gallus gallus. Chicken. Organism_taxid: 9031. Gene: ovalbumin. Expressed in: escherichia coli bl21(de3). Expression_system_taxid: 469008.

Resolution:

2.30Å R-factor: 0.199 R-free: 0.252

Authors:

M.Yamasaki,Y.Arii,B.Mikami,M.Hirose

Key ref:

M.Yamasaki et al. (2002). Loop-inserted and thermostabilized structure of P1-P1' cleaved ovalbumin mutant R339T. J Mol Biol, 315, 113-120. PubMed id: 11779232 DOI: 10.1006/jmbi.2001.5056

Date:

21-Aug-01 Release date: 05-Sep-01

Protein chains

P01012  (OVAL_CHICK) -  Ovalbumin from Gallus gallus

Seq: 386 a.a.

Struc: 381 a.a.*

* PDB and UniProt seqs differ at 2 residue positions (black crosses)

DOI no: 10.1006/jmbi.2001.5056

J Mol Biol 315:113-120 (2002)

PubMed id: 11779232

Loop-inserted and thermostabilized structure of P1-P1' cleaved ovalbumin mutant R339T.

M.Yamasaki, Y.Arii, B.Mikami, M.Hirose.

ABSTRACT

Ovalbumin is a member of a superfamily of serine proteinase inhibitors, known as the serpins. It is, however, non-inhibitory towards serine proteinases, and lacks the loop insertion mechanism common to the serpins due to unknown structural factors. Mutant ovalbumin, R339T, in which the P14 hinge residue is replaced, was produced and analyzed for its thermostability and three-dimensional structure. Differential scanning calorimetry revealed that the mutant ovalbumin, but not the wild-type protein, undergoes a marked thermostabilization (DeltaT(m)=15.8 degrees C) following the P1-P1' cleavage. Furthermore, the crystal structure, solved at 2.3 A resolution, clearly proved that the P1-P1' cleaved form assumes the fully loop-inserted conformation as seen in serpin that possess inhibitory activity. We therefore conclude that ovalbumin acquires the structural transition mechanism into the loop-inserted, thermostabilized form by the single hinge mutation. The mutant protein does not, however, possess inhibitory activity. The solved structure displays the occurrence of specific interactions that may prevent the smooth motion, relative to sheet A, of helices E and F and of the loop that follows helix F. These observations provide crucial insights into the question why R339T is still non-inhibitory.

Selected figure(s)

Figure 2.
Figure 2. Stereo diagrams of P1-P1' cleaved R339T structure. (a) C^a plots of the P1-P1' cleaved R339T. The a-helices and b-strands are shown in green and yellow, respectively. The b-strand, shown in orange, represents the inserted strand 4A. The Figures were produced with MOLSCRIPT[28] and Raster3D. [29] (b) Electron density map (2F[o] -F[c] contoured at 1s) of sheet A. The main chain hydrogen bonds with a donor-acceptor distance less than 3.3 Å are shown by red broken lines.

Figure 4.
Figure 4. Interactions of helix F and its descending loop with sheet A. C^a traces for (a) intact egg white ovalbumin and for (b) P1-P1' cleaved R339T are shown in white except that the reactive center loop or inserted b-strand is represented in orange. The main chain atoms involved in hydrogen bonds are shown in the standard colors. The side-chain groups of Arg104, Trp148, Lys290 and Gln325 are shown in red, yellow, blue and green, respectively. The indole plane of Trp148 and the plane formed by the N epsilon , C^z, Nr1, and Nr2 atoms of Arg104 intersect with dihedral angles of 12.7 ° and 10.2 ° in the intact and cleaved forms, respectively. The shortest distance between the two planes are 3.3 Å for the Arg104-Nr1 to Trp148-N1 distance in intact ovalbumin and 3.1 Å for the Arg104-Nr1 to Trp148-C^d1 distance in cleaved R339T.

The above figures are reprinted by permission from Elsevier: J Mol Biol (2002, 315, 113-120) copyright 2002.

Figures were selected by an automated process.