PDBsum entry 1pju

Hydrolase

PDB id: 1pju

Contents

Protein chains

115 a.a. *

Ligands

SO4 ×8

Waters ×175

* Residue conservation analysis

PDB id:

1pju

Name:

Hydrolase

Title:

Unbound form of tomato inhibitor-ii

Structure:

Wound-induced proteinase inhibitor ii. Chain: a, b, c, d

Source:

Solanum lycopersicum. Organism_taxid: 4081. Strain: bonny best

Biol. unit:

Tetramer (from PQS)

Resolution:

2.15Å R-factor: 0.208 R-free: 0.250

Authors:

I.H.Barrette-Ng,K.K.-S.Ng,M.M.Cherney,G.Pearce,U.Ghani,C.A.Ryan, M.N.G.James

Key ref:

I.H.Barrette-Ng et al. (2003). Unbound form of tomato inhibitor-II reveals interdomain flexibility and conformational variability in the reactive site loops. J Biol Chem, 278, 31391-31400. PubMed id: 12788916 DOI: 10.1074/jbc.M304562200

Date:

03-Jun-03 Release date: 16-Sep-03

Protein chains

P05119  (IP21_SOLLC) -  Wound-induced proteinase inhibitor 2 from Solanum lycopersicum

Seq: 148 a.a.

Struc: 115 a.a.

DOI no: 10.1074/jbc.M304562200

J Biol Chem 278:31391-31400 (2003)

PubMed id: 12788916

Unbound form of tomato inhibitor-II reveals interdomain flexibility and conformational variability in the reactive site loops.

I.H.Barrette-Ng, K.K.Ng, M.M.Cherney, G.Pearce, U.Ghani, C.A.Ryan, M.N.James.

ABSTRACT

The Potato II (Pot II) family of proteinase inhibitors plays important roles in the constitutive and inducible defense of plants against predation by a wide range of pests. The structural basis of inhibition by a multidomain Pot II family inhibitor was revealed recently by the structure of the ternary complex between the two-headed tomato inhibitor-II (TI-II) and two molecules of subtilisin Carlsberg. Here we report the 2.15-A resolution crystal structure of the unbound form of TI-II that reveals significant conformational flexibility in the absence of bound proteinase molecules. The four independent copies of unbound TI-II in the asymmetric unit of the unit cell display a range of different conformations when compared with the bound form of the inhibitor, most strikingly in the orientations of the inhibitory domains and in the conformations of the reactive site loops. One of the two linker segments (residues 74 to 79) between the two domains as well as the adjacent beta-strand in Domain I (residues 80-85) is well ordered in all four copies of the unbound inhibitor, even though this region appeared to be disordered in the structure of the ternary complex. Conformational flexibility seen in the reactive site loops of unbound TI-II suggests a mechanism by which the inhibitor can balance the need for tight binding with the need for broad inhibitory function.

Selected figure(s)

Figure 2.
FIG. 2. Conformational change in linker region of unbound TI-II. A stereoscopic view of linker residues 15-18 (shown in magenta) and residues 76-80 (shown in black) of copy A (A) and copy B (B) is shown. Omit map electron density corresponding to Arg-17 has been contoured at 3.4 .

Figure 3.
FIG. 3. Least-squares superpositions of unbound TI-II onto bound TI-II. A stereoscopic view of a least-squares superposition of copies A and B (A) and copies C and D (B) onto the structure of TI-II from the TI-II:(subtilisin)[2] complex is shown. The bound form of TI-II is drawn in magenta, whereas the unbound forms are shown in red in Domain I and blue in Domain II.

The above figures are reprinted by permission from the ASBMB: J Biol Chem (2003, 278, 31391-31400) copyright 2003.

Figures were selected by an automated process.