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PDBsum entry 1oyv
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Contents |
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* Residue conservation analysis
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References listed in PDB file
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Key reference
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Title
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Structural basis of inhibition revealed by a 1:2 complex of the two-Headed tomato inhibitor-Ii and subtilisin carlsberg.
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Authors
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I.H.Barrette-Ng,
K.K.Ng,
M.M.Cherney,
G.Pearce,
C.A.Ryan,
M.N.James.
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Ref.
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J Biol Chem, 2003,
278,
24062-24071.
[DOI no: ]
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PubMed id
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Abstract
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Multidomain proteinase inhibitors play critical roles in the defense of plants
against predation by a wide range of pests. Despite a wealth of structural
information on proteinase-single domain inhibitor interactions, the structural
basis of inhibition by multidomain proteinase inhibitors remains poorly
understood. Here we report the 2.5-A resolution crystal structure of the
two-headed tomato inhibitor-II (TI-II) in complex with two molecules of
subtilisin Carlsberg; it reveals how a multidomain inhibitor from the Potato II
family of proteinase inhibitors can bind to and simultaneously inhibit two
enzyme molecules within a single ternary complex. The N terminus of TI-II
initiates the folding of Domain I (Lys-1 to Cys-15 and Pro-84 to Met-123) and
then completes Domain II (Ile-26 to Pro-74) before coming back to complete the
rest of Domain I (Pro-84 to Met-123). The two domains of TI-II adopt a similar
fold and are arranged in an extended configuration that presents two reactive
site loops at the opposite ends of the inhibitor molecule. Each subtilisin
molecule interacts with a reactive site loop of TI-II through the standard,
canonical binding mode. Remarkably, a significant distortion of the active site
of subtilisin is induced by the presence of phenylalanine in the P1 position of
reactive site loop II of TI-II. The structure of the TI-II.(subtilisin)2 complex
provides a molecular framework for understanding how multiple inhibitory domains
in a single Potato II type proteinase inhibitor molecule from the Potato II
family act to inhibit proteolytic enzymes.
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Figure 4.
FIG. 4. Conformations of the reactive site loops. A,
stereoscopic view of a superposition of the reactive site loops
of both domains. Conformation of the reactive site loops of
Domain I (B) and Domain II (C) bound to subtilisin are shown.
The solvent-accessible surface of the subtilisin molecules are
drawn with negatively charged residues colored red, positively
charged residues colored blue, and hydrophobic residues colored
magenta.
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Figure 5.
FIG. 5. Interactions between subtilisin and TI-II. Shown is
a stylized representation of the interactions between subtilisin
and the reactive site loops of Domain I (A) and Domain II (B).
Residues of subtilisin making van der Waals interactions with
the reactive site loops of TI-II are shown as blue circles and,
in some instances, as parallel lines. Also shown is a
stereoscopic view of the interactions between subtilisin and the
reactive site loops of Domain I (C) and Domain II (D). Inhibitor
is green, and subtilisin is black.
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The above figures are
reprinted
by permission from the ASBMB:
J Biol Chem
(2003,
278,
24062-24071)
copyright 2003.
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