PDBsum entry: 1exg

Cellulose degradation

PDB id: 1exg

Contents

Protein chain

110 a.a. *

* Residue conservation analysis

PDB id:

1exg

Name:

Cellulose degradation

Title:

Solution structure of a cellulose binding domain from cellulomonas fimi by nuclear magnetic resonance spectroscopy

Structure:

Exo-1,4-beta-d-glycanase. Chain: a. Engineered: yes

Source:

Cellulomonas fimi. Organism_taxid: 1708

NMR struc:

1 models

Authors:

G.-Y.Xu,E.Ong,N.R.Gilkes,D.G.Kilburn,D.R.Muhandiram, M.Harris-Brandts,J.P.Carver,L.E.Kay,T.S.Harvey

Key ref:

G.Y.Xu et al. (1995). Solution structure of a cellulose-binding domain from Cellulomonas fimi by nuclear magnetic resonance spectroscopy. Biochemistry, 34, 6993-7009. PubMed id: 7766609 DOI: 10.1021/bi00021a011

Date:

14-Mar-95 Release date: 03-Jun-95

Protein chain

P07986  (GUX_CELFI) -  Exoglucanase/xylanase

Seq: 484 a.a.

Struc: 110 a.a.*

* PDB and UniProt seqs differ at 2 residue positions (black crosses)

Enzyme reactions

• Enzyme class 1: E.C.3.2.1.8 - Endo-1,4-beta-xylanase.
• Reaction: Endohydrolysis of 1,4-beta-D-xylosidic linkages in xylans.
• Enzyme class 2: E.C.3.2.1.91 - Cellulose 1,4-beta-cellobiosidase (non-reducing end).
• Reaction: Hydrolysis of 1,4-beta-D-glucosidic linkages in cellulose and cellotetraose, releasing cellobiose from the non-reducing ends of the chains.

Note, where more than one E.C. class is given (as above), each may correspond to a different protein domain or, in the case of polyprotein precursors, to a different mature protein.

 Gene Ontology (GO) functional annotation 

• Biological process: carbohydrate metabolic process (1 term)
• Biochemical function: carbohydrate binding (3 terms)

DOI no: 10.1021/bi00021a011

Biochemistry 34:6993-7009 (1995)

PubMed id: 7766609

Solution structure of a cellulose-binding domain from Cellulomonas fimi by nuclear magnetic resonance spectroscopy.

G.Y.Xu, E.Ong, N.R.Gilkes, D.G.Kilburn, D.R.Muhandiram, M.Harris-Brandts, J.P.Carver, L.E.Kay, T.S.Harvey.

ABSTRACT

Multidimensional, multinuclear nuclear magnetic resonance spectroscopy combined with dynamical simulated annealing has been used to determine the structure of a 110 amino acid cellulose-binding domain (CBD) from Cex, a beta-1,4-glycanase from the bacterium Cellulomonas fimi (CBDcex). An experimental data set comprising 1795 interproton NOE-derived restraints, 50 phi, 34 chi 1, and 106 hydrogen bond restraints was used to calculate 20 final structures. The calculated structures have an average root-mean-square (rms) deviation about the mean structure of 0.41 A for backbone atoms and 0.67 A for all heavy atoms when fitted over the secondary structural elements. Chromatography, ultracentrifugation, and 15N NMR relaxation experiments demonstrate that CBDcex is a dimer in solution. While attempts to measure NOEs across the dimer interface were unsuccessful, a computational strategy was employed to generate dimer structures consistent with the derived data set. The results from the dimer calculations indicate that, while the monomer topologies produced in the context of the dimer can be variable, the relative positioning of secondary structural elements and side chains present in the monomer are restored upon dimer formation. CBDcex forms an extensive beta-sheet structure with a beta-barrel fold. Titration with cellohexaose, [beta-D-glucopyranosyl-(1,4)]5-D-glucose, establishes that Trp 54 and 72 participate in cellulose binding. Analysis of the structure shows that these residues are adjacent in space and exposed to solvent. Together with other proximate hydrophilic residues, these residues form a carbohydrate-binding cleft, which appears to be a feature common to all CBDs of the same family.