PDBsum entry 2pwg

Isomerase

PDB id: 2pwg

Contents

Protein chains

556 a.a. *

Ligands

CTS ×2

Metals

_CA ×2

Waters ×1367

* Residue conservation analysis

PDB id:

2pwg

Name:

Isomerase

Title:

Crystal structure of the trehalulose synthase mutb from pseudomonas mesoacidophila mx-45 complexed to the inhibitor castanospermine

Structure:

Sucrose isomerase. Chain: a, b. Engineered: yes

Source:

Pseudomonas mesoacidophila. Organism_taxid: 265293. Strain: mx-45. Gene: mutb. Expressed in: escherichia coli. Expression_system_taxid: 562.

Resolution:

2.20Å R-factor: 0.186 R-free: 0.230

Authors:

S.Ravaud,X.Robert,R.Haser,N.Aghajari

Key ref:

S.Ravaud et al. (2007). Trehalulose synthase native and carbohydrate complexed structures provide insights into sucrose isomerization. J Biol Chem, 282, 28126-28136. PubMed id: 17597061 DOI: 10.1074/jbc.M704515200

Date:

11-May-07 Release date: 26-Jun-07

Protein chains

Q2PS28  (Q2PS28_9BURK) -  Sucrose isomerase from Burkholderia ubonensis subsp. mesacidophila

Seq: 584 a.a.

Struc: 556 a.a.

Enzyme reactions

• Enzyme class: E.C.5.4.99.11 - isomaltulose synthase.
• Reaction: sucrose = 6-O-alpha-D-glucopyranosyl-D-fructose

Molecule diagrams generated from .mol files obtained from the KEGG ftp site

Key reference

DOI no: 10.1074/jbc.M704515200

J Biol Chem 282:28126-28136 (2007)

PubMed id: 17597061

Trehalulose synthase native and carbohydrate complexed structures provide insights into sucrose isomerization.

S.Ravaud, X.Robert, H.Watzlawick, R.Haser, R.Mattes, N.Aghajari.

ABSTRACT

Various diseases related to the overconsumption of sugar make a growing need for sugar substitutes. Because sucrose is an inexpensive and readily available d-glucose donor, the industrial potential for enzymatic synthesis of the sucrose isomers trehalulose and/or isomaltulose from sucrose is large. The product specificity of sucrose isomerases that catalyze this reaction depends essentially on the possibility for tautomerization of sucrose, which is required for trehalulose formation. For optimal use of the enzyme, targeting controlled synthesis of these functional isomers, it is necessary to minimize the side reactions. This requires an extensive analysis of substrate binding modes and of the specificity-determining sites in the structure. The 1.6-2.2-A resolution three-dimensional structures of native and mutant complexes of a trehalulose synthase from Pseudomonas mesoacidophila MX-45 mimic successive states of the enzyme reaction. Combined with mutagenesis studies they give for the first time thorough insights into substrate recognition and processing and reaction specificities of these enzymes. Among the important outcomes of this study is the revelation of an aromatic clamp defined by Phe(256) and Phe(280) playing an essential role in substrate recognition and in controlling the reaction specificity, which is further supported by mutagenesis studies. Furthermore, this study highlights essential residues for binding the glucosyl and fructosyl moieties. The introduction of subtle changes informed by comparative three-dimensional structural data observed within our study can lead to fundamental modifications in the mode of action of sucrose isomerases and hence provide a template for industrial catalysts.

Selected figure(s)

Figure 1.
FIGURE 1. Schematic drawings of the products trehalulose (A) and isomaltulose (B) and of the substrate sucrose (C).

Figure 5.
FIGURE 5. Close up on the active sites of native MutB (A), E254Q·sucrose (B), MutB·castanospermine (C), MutB·deoxynojirimycin (D), and D200A·glucose (E). Electron density 2F[o] - F[c] maps are contoured at 1 . Catalytic residues are highlighted in green, and other active site residues are in yellow. The aromatic clamp in magenta corresponds to conformation 1, and that in cyan corresponds to conformation 2.

The above figures are reprinted by permission from the ASBMB: J Biol Chem (2007, 282, 28126-28136) copyright 2007.

Figures were selected by an automated process.