PDBsum entry: 2zew

Hydrolase

PDB id: 2zew

Contents

Protein chains

146 a.a. *

Metals

_CA ×2

Waters ×341

* Residue conservation analysis

PDB id:

2zew

Name:

Hydrolase

Title:

Family 16 cabohydrate binding domain module 1

Structure:

S-layer associated multidomain endoglucanase. Chain: a, b. Fragment: cbm-1, unp residues 610-756. Synonym: family 16 carbohydrate binding module-1 from mana. Engineered: yes

Source:

Thermoanaerobacterium polysaccharolyticum. Organism_taxid: 44256. Gene: cela. Expressed in: escherichia coli bl21(de3). Expression_system_taxid: 469008.

Resolution:

1.40Å R-factor: 0.178 R-free: 0.197

Authors:

B.Bae,S.K.Nair

Key ref:

B.Bae et al. (2008). Molecular basis for the selectivity and specificity of ligand recognition by the family 16 carbohydrate-binding modules from Thermoanaerobacterium polysaccharolyticum ManA. J Biol Chem, 283, 12415-12425. PubMed id: 18025086 DOI: 10.1074/jbc.M706513200

Date:

18-Dec-07 Release date: 04-Mar-08

Protein chains

Q9ZA17  (Q9ZA17_9THEO) -  S-layer associated multidomain endoglucanase

Seq: 1097 a.a.

Struc: 146 a.a.*

* PDB and UniProt seqs differ at 3 residue positions (black crosses)

DOI no: 10.1074/jbc.M706513200

J Biol Chem 283:12415-12425 (2008)

PubMed id: 18025086

Molecular basis for the selectivity and specificity of ligand recognition by the family 16 carbohydrate-binding modules from Thermoanaerobacterium polysaccharolyticum ManA.

B.Bae, S.Ohene-Adjei, S.Kocherginskaya, R.I.Mackie, M.A.Spies, I.K.Cann, S.K.Nair.

ABSTRACT

Enzymes that hydrolyze complex polysaccharides into simple sugars are modular in architecture and consist of single or multiple catalytic domains fused to targeting modules called carbohydrate-binding modules (CBMs). CBMs bind to their ligands with high affinity and increase the efficiency of the catalytic components by targeting the enzymes to its substrate. Here we utilized a multidisciplinary approach to characterize each of the two family 16 carbohydrate-binding domain components of the highly active mannanase from the thermophile Thermoanaerobacterium polysaccharolyticum. These represent the first crystal structures of family 16 CBMs. Calorimetric analysis showed that although these CBMs demonstrate high specificity toward beta-1,4-linked sugars, they can engage both cello- and mannopolysaccharides. To elucidate the molecular basis for this specificity and selectivity, we have determined high resolution crystal structures of each of the two CBMs, as well as of binary complexes of CBM16-1 bound to either mannopentaose or cellopentaose. These results provide detailed molecular insights into ligand recognition and yield a framework for rational engineering experiments designed to expand the natural repertoire of these targeting modules.

Selected figure(s)

Figure 2.
FIGURE 2. A, ribbon diagram of the overall structures of TpolCBM16-1 bound to the β-1,4-glucan polysaccharide substrate, cellopentaose. The protein is colored as in Fig. 1A, and the polysaccharide is shown in a ball-and-stick representation. B, surface representation of TpolCBM16-1, with the corresponding electrostatic potential, shows that the β-1,4-glucan binds in a surface cleft that is perpendicular to the orientation of the β-sheet structure.

Figure 3.
FIGURE 3. A, difference Fourier electron density maps (contoured at 3 over background) calculated with coefficients F[obs] - F[calc] at the ligand-binding site for the 1.2 Å resolution TpolCBM16-1-cellopentaose complex. B, direct hydrogen bonding interactions between residues of TpolCBM16-1 and cellopentaose. C, difference Fourier electron density maps (contoured at 3 over background) calculated with coefficients F[obs] - F[calc] at the ligand-binding site for the 2.2 Å resolution TpolCBM16-1-mannopentaose complex. D, direct hydrogen bonding interactions between residues of TpolCBM16-1 and mannopentaose.

The above figures are reprinted by permission from the ASBMB: J Biol Chem (2008, 283, 12415-12425) copyright 2008.

Figures were selected by an automated process.