2hgo
NMR structure of CassiicolinNMR structure of Cassiicolin
Structural highlights
FunctionCASSI_CORCC Toxin, essential for pathogenicity. Causes symptoms of Corynespora leaf fall disease (CLF) in rubber trees, including chlorosis, development of brown spots and necrosis. Alters leaf cell ultrastructure, causing plasmolysis in most cell types. In extreme cases the plasmolysis leads to disruption of the plasma membrane. Also affects chloroplast structure, causing lamellae distortion and reduced thylakoids stacking together. Causes accumulation of starch grains. Does not affect the nucleus or mitochondria. Toxic to N.tabacum, L.esculentum, S.ionantha, F.lyrata, P.violacea, S.melongena, and G.max. Not toxic to P.alba, G.hirsutum, P.acerifolia, R.pseudoacacia, T.zebrina, M.alba, and Q.ilex.[1] [2] [3] Publication Abstract from PubMedCassiicolin is a host-selective toxin (HST) produced by the fungus Corynespora cassiicola (strain CCP). It is responsible for the Corynespora leaf fall (CLF) disease, which is among the main pathologies affecting rubber tree (Hevea brasiliensis). Working on purified cassiicolin and using electron microscopy, we have demonstrated that this 27-residue O-glycosylated protein is able to induce cellular damages identical to those induced by the fungus on rubber tree leaves and displays the same host selectivity. The solution structure and disulfide pairing of cassiicolin have been determined using NMR spectroscopy and simulated annealing calculations. Cassiicolin appears to have an original structure with a prolate ellipsoid shape. It adopts an over-all fold consisting of three strands arranged in a right-handed twisted, antiparallel beta-sheet knitted by three disulfide bonds. Its conformation resembles that found in small trypsine-like inhibitors isolated from the brain, the fat body and the hemolymph of locust grasshoppers. But cassiicolin has no sequence homology with these protease inhibitors, and lacks their characteristic substrate-binding loop. Probably, this motif represents one of the few highly stabilized "minimal" scaffolds, with a high sequence permissiveness, that nature has selected to evolve over different phyla and to support different functions. The knowledge of the 3D structure opens the way to the delineation of the mechanism of action of the toxin using site-directed mutagenesis. Structural analysis of cassiicolin, a host-selective protein toxin from Corynespora cassiicola.,Barthe P, Pujade-Renaud V, Breton F, Gargani D, Thai R, Roumestand C, de Lamotte F J Mol Biol. 2007 Mar 16;367(1):89-101. Epub 2006 Dec 5. PMID:17234212[4] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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