PDBsum entry 2hgo

Toxin

PDB id: 2hgo

Contents

Protein chain

27 a.a.

Ligands

3HD

PDB id:

2hgo

Name:

Toxin

Title:

Nmr structure of cassiicolin

Structure:

Cassiicolin. Chain: a. Engineered: yes

Source:

Corynespora cassiicola. Organism_taxid: 59586. Expressed in: corynespora cassiicola. Expression_system_taxid: 59586

NMR struc:

20 models

Authors:

P.Barthe,V.Pujade-Renault,C.Roumestand,F.De Lamotte

Key ref:

P.Barthe et al. (2007). Structural analysis of cassiicolin, a host-selective protein toxin from Corynespora cassiicola. J Mol Biol, 367, 89. PubMed id: 17234212 DOI: 10.1016/j.jmb.2006.11.086

Date:

27-Jun-06 Release date: 27-Feb-07

Protein chain

P84902  (CASSI_CORCC) -  Cassiicolin from Corynespora cassiicola

Seq: 27 a.a.

Struc: 27 a.a.*

* PDB and UniProt seqs differ at 1 residue position (black cross)

DOI no: 10.1016/j.jmb.2006.11.086

J Mol Biol 367:89 (2007)

PubMed id: 17234212

Structural analysis of cassiicolin, a host-selective protein toxin from Corynespora cassiicola.

P.Barthe, V.Pujade-Renaud, F.Breton, D.Gargani, R.Thai, C.Roumestand, F.de Lamotte.

ABSTRACT

Cassiicolin 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.

Selected figure(s)

Figure 4.
Figure 4. Cassiicolin is O-glycosylated on Thr2. (a) Superimposition of the sugar region of the [^1H-^13C]HSQC (red) and [^1H-^13C]HSQC-TOCSY (black) (mixing times 16 ms) spectra of cassiicolin. The walk from anomeric ^13C and ^1H resonances across the full sub-spectra of the sugar moiety is indicated by the continuous line. The corresponding direct connectivities are labelled in the HSQC spectrum. (b) and (c) Strips extracted from the ge-HMBC spectrum showing (dotted lines) the connectivity between the anomeric proton of the sugar and the C^β of Thr2 (b) and the methylation of the mannose C3 (c). The corresponding trace of the 1D spectrum is indicated on top of each 2D plot. Figure 4. Cassiicolin is O-glycosylated on Thr2. (a) Superimposition of the sugar region of the [^1H-^13C]HSQC (red) and [^1H-^13C]HSQC-TOCSY (black) (mixing times 16 ms) spectra of cassiicolin. The walk from anomeric ^13C and ^1H resonances across the full sub-spectra of the sugar moiety is indicated by the continuous line. The corresponding direct connectivities are labelled in the HSQC spectrum. (b) and (c) Strips extracted from the ge-HMBC spectrum showing (dotted lines) the connectivity between the anomeric proton of the sugar and the C^β of Thr2 (b) and the methylation of the mannose C3 (c). The corresponding trace of the 1D spectrum is indicated on top of each 2D plot.

Figure 6.
Figure 6. 3D Solution structure of cassiicolin. The refined structure of cassiicolin. (a) Two views of the 20 best structures of cassiicolin, superimposed over the backbone heavy atoms N, C^α and C′. Only backbone atoms are shown, except for the three disulfide bridges (green). (b) The same two views of the ribbon plot of the structure of cassiicolin, which is closest to the average. Side-chains are displayed using a stick representation and the following color code: green for hydrophobic residues, orange for uncharged polar residues, and red for acidic residues. (c) The same two views of the surface representation of the structure of cassiicolin, using the same color code as in (b). The two views are related by a 180° rotation about the major axis of the protein. Figure 6. 3D Solution structure of cassiicolin. The refined structure of cassiicolin. (a) Two views of the 20 best structures of cassiicolin, superimposed over the backbone heavy atoms N, C^α and C′. Only backbone atoms are shown, except for the three disulfide bridges (green). (b) The same two views of the ribbon plot of the structure of cassiicolin, which is closest to the average. Side-chains are displayed using a stick representation and the following color code: green for hydrophobic residues, orange for uncharged polar residues, and red for acidic residues. (c) The same two views of the surface representation of the structure of cassiicolin, using the same color code as in (b). The two views are related by a 180° rotation about the major axis of the protein.

The above figures are reprinted by permission from Elsevier: J Mol Biol (2007, 367, 89-0) copyright 2007.

Figures were selected by the author.