1pju
From Proteopedia
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Unbound form of Tomato Inhibitor-II
Overview
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.
About this Structure
1PJU is a Single protein structure of sequence from Solanum lycopersicum with SO4 as ligand. Full crystallographic information is available from OCA.
Reference
Unbound form of tomato inhibitor-II reveals interdomain flexibility and conformational variability in the reactive site loops., Barrette-Ng IH, Ng KK, Cherney MM, Pearce G, Ghani U, Ryan CA, James MN, J Biol Chem. 2003 Aug 15;278(33):31391-400. Epub 2003 Jun 4. PMID:12788916
Page seeded by OCA on Tue Nov 20 23:52:25 2007
