2c1c: Difference between revisions
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[[Category: plant inhibitors]] | [[Category: plant inhibitors]] | ||
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Revision as of 18:50, 5 November 2007
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STRUCTURAL BASIS OF THE RESISTANCE OF AN INSECT CARBOXYPEPTIDASE TO PLANT PROTEASE INHIBITORS
OverviewOverview
Corn earworm (Helicoverpa zea), also called tomato fruitworm, is a common, pest of many Solanaceous plants. This insect is known to adapt to the, ingestion of plant serine protease inhibitors by using digestive proteases, that are insensitive to inhibition. We have now identified a B-type, carboxypeptidase of H. zea (CPBHz) insensitive to potato carboxypeptidase, inhibitor (PCI) in corn earworm. To elucidate the structural features, leading to the adaptation of the insect enzyme, the crystal structure of, the recombinant CPBHz protein was determined by x-ray diffraction. CPBHz, is a member of the A/B subfamily of metallocarboxypeptidases, which, displays the characteristic metallocarboxypeptidase alpha/beta-hydrolase, fold, and does not differ essentially from the previously described, Helicoverpa armigera CPA, which is very sensitive to PCI. The data provide, structural insight into several functional properties of CPBHz. The high, selectivity shown by CPBHz for C-terminal lysine residues is due to, residue changes in the S1' substrate specificity pocket that render it, unable to accommodate the side chain of an arginine. The insensitivity of, CPBHz to plant inhibitors is explained by the exceptional positioning of, two of the main regions that stabilize other carboxypeptidase-PCI, complexes, the beta8-alpha9 loop, and alpha7 together with the, alpha7-alpha8 loop. The rearrangement of these two regions leads to a, displacement of the active-site entrance that impairs the proper, interaction with PCI. This report explains a crystal structure of an, insect protease and its adaptation to defensive plant protease inhibitors.
About this StructureAbout this Structure
2C1C is a Single protein structure of sequence from Helicoverpa zea with ZN and Y1 as ligands. Active as Carboxypeptidase B, with EC number 3.4.17.2 Structure known Active Site: AC1. Full crystallographic information is available from OCA.
ReferenceReference
Structural basis of the resistance of an insect carboxypeptidase to plant protease inhibitors., Bayes A, Comellas-Bigler M, Rodriguez de la Vega M, Maskos K, Bode W, Aviles FX, Jongsma MA, Beekwilder J, Vendrell J, Proc Natl Acad Sci U S A. 2005 Nov 15;102(46):16602-7. Epub 2005 Oct 31. PMID:16260742
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