PDBsum entry: 2cyg

Hydrolase

PDB id: 2cyg

Contents

Protein chain

312 a.a. *

Waters ×407

* Residue conservation analysis

PDB id:

2cyg

Name:

Hydrolase

Title:

Crystal structure at 1.45- resolution of the major allergen endo-beta-1,3-glucanase of banana as a molecular basis for the latex-fruit syndrome

Structure:

Beta-1, 3-glucananse. Chain: a. Synonym: endo-beta-1,3-glucanase. Ec: 3.2.1.39

Source:

Musa acuminata. Organism_taxid: 4641

Resolution:

1.45Å R-factor: 0.158 R-free: 0.179

Authors:

V.Receveur-Brechot,M.Czjzek,A.Barre,A.Roussel,W.J.Peumans, E.J.M.Van Damme,P.Rouge

Key ref:

V.Receveur-Bréchot et al. (2006). Crystal structure at 1.45-A resolution of the major allergen endo-beta-1,3-glucanase of banana as a molecular basis for the latex-fruit syndrome. Proteins, 63, 235-242. PubMed id: 16421930 DOI: 10.1002/prot.20876

Date:

07-Jul-05 Release date: 22-Nov-05

Protein chain

O22317  (O22317_MUSAC) -  Beta-1, 3-glucananse

Seq: 340 a.a.

Struc: 312 a.a.*

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

 Gene Ontology (GO) functional annotation 

• Biological process: metabolic process (2 terms)
• Biochemical function: catalytic activity (5 terms)

DOI no: 10.1002/prot.20876

Proteins 63:235-242 (2006)

PubMed id: 16421930

Crystal structure at 1.45-A resolution of the major allergen endo-beta-1,3-glucanase of banana as a molecular basis for the latex-fruit syndrome.

V.Receveur-Bréchot, M.Czjzek, A.Barre, A.Roussel, W.J.Peumans, E.J.Van Damme, P.Rougé.

ABSTRACT

Resolution of the crystal structure of the banana fruit endo-beta-1,3-glucanase by synchrotron X-ray diffraction at 1.45-A resolution revealed that the enzyme possesses the eightfold beta/alpha architecture typical for family 17 glycoside hydrolases. The electronegatively charged catalytic central cleft harbors the two glutamate residues (Glu94 and Glu236) acting as hydrogen donor and nucleophile residue, respectively. Modeling using a beta-1,3 linked glucan trisaccharide as a substrate confirmed that the enzyme readily accommodates a beta-1,3-glycosidic linkage in the slightly curved catalytic groove between the glucose units in positions -2 and -1 because of the particular orientation of residue Tyr33 delimiting subsite -2. The location of Phe177 in the proximity of subsite +1 suggested that the banana glucanase might also cleave beta-1,6-branched glucans. Enzymatic assays using pustulan as a substrate demonstrated that the banana glucanase can also cleave beta-1,6-glucans as was predicted from docking experiments. Similar to many other plant endo-beta-1,3-glucanases, the banana glucanase exhibits allergenic properties because of the occurrence of well-conserved IgE-binding epitopes on the surface of the enzyme. These epitopes might trigger some cross-reactions toward IgE antibodies and thus account for the IgE-binding cross-reactivity frequently reported in patients with the latex-fruit syndrome.

Selected figure(s)

Figure 1.
Figure 1. A: Stereo view of the ribbon diagram showing the overall ( / )[8] TIM-barrel structure of Ban-Gluc. The strands of -sheet (light green arrows) surrounded by the -helices (colored red brown) form the ( / )[8] M-barrel. Numbers 1 and 312 indicate the N- and C-terminal ends of the polypeptide chain, respectively. B: Enlarged ribbon diagram of the catalytic groove of Ban-Gluc located at the bottom of the ( / )[8] TIM-barrel, together with a modeled -1,3-glucan (sandy-brown) at subsites -2, -1, and +1. Catalytic residues (E94, E236), the residues putatively involved in substrate binding (N93, E294, Y174), and the aromatic residues (Y33, F177, F281, F297) stacking the sugar rings of the substrate, are in ball and stick representation. C: Electrostatic potential map of Ban-Gluc showing the electronegative character of the catalytic groove. Negative and positive potentials are colored red and blue and displayed at -7 kT and +7 kT level (1 kT = 0.6 kcals), respectively. Neutral surfaces are colored white. The curved dashed line indicates the central catalytic groove. D: Front view of the ribbon diagram of Ban-Gluc showing the location of the predicted T-cell epitopes. Major T-cell epitopes are numbered in bold and colored magenta (epitope 1), light blue (epitope 4), yellow (epitope 5), green (epitope 7), red (epitope 8),and black (epitope 9). E: Surface occupied on the molecular surface of the front face of Ban-Gluc by the predicted IgE-binding epitopes. Other not-shown predicted epitopes (4, 8, 13, 14) occur at the opposite face of the TIM-barrel.

Figure 2.
Figure 2. Release of glucose from pustulan by Ban-Gluc. Activity is expressed as nanomole glucose released per milligram enzyme.

The above figures are reprinted by permission from John Wiley & Sons, Inc.: Proteins (2006, 63, 235-242) copyright 2006.

Figures were selected by an automated process.