PDBsum entry 1m7x

Transferase

PDB id: 1m7x

Contents

Protein chains

587 a.a. *

Waters ×1142

* Residue conservation analysis

PDB id:

1m7x

Name:

Transferase

Title:

The x-ray crystallographic structure of branching enzyme

Structure:

1,4-alpha-glucan branching enzyme. Chain: a, b, c, d. Fragment: residues 113-728. Synonym: glycogen branching enzyme. Engineered: yes

Source:

Escherichia coli. Organism_taxid: 562. Expressed in: escherichia coli. Expression_system_taxid: 562.

Resolution:

2.30Å R-factor: 0.200 R-free: 0.265

Authors:

M.C.Abad,K.Binderup,J.Rios-Steiner,R.K.Arni,J.Preiss,J.H.Geiger

Key ref:

M.C.Abad et al. (2002). The X-ray crystallographic structure of Escherichia coli branching enzyme. J Biol Chem, 277, 42164-42170. PubMed id: 12196524 DOI: 10.1074/jbc.M205746200

Date:

23-Jul-02 Release date: 18-Sep-02

Protein chains

P07762  (GLGB_ECOLI) -  1,4-alpha-glucan branching enzyme GlgB from Escherichia coli (strain K12)

Seq: 728 a.a.

Struc: 587 a.a.

Enzyme reactions

• Enzyme class: E.C.2.4.1.18 - 1,4-alpha-glucan branching enzyme.
• Reaction: Formation of 1,6-glucosidic linkages of glycogen.

DOI no: 10.1074/jbc.M205746200

J Biol Chem 277:42164-42170 (2002)

PubMed id: 12196524

The X-ray crystallographic structure of Escherichia coli branching enzyme.

M.C.Abad, K.Binderup, J.Rios-Steiner, R.K.Arni, J.Preiss, J.H.Geiger.

ABSTRACT

Branching enzyme catalyzes the formation of alpha-1,6 branch points in either glycogen or starch. We report the 2.3-A crystal structure of glycogen branching enzyme from Escherichia coli. The enzyme consists of three major domains, an NH(2)-terminal seven-stranded beta-sandwich domain, a COOH-terminal domain, and a central alpha/beta-barrel domain containing the enzyme active site. While the central domain is similar to that of all the other amylase family enzymes, branching enzyme shares the structure of all three domains only with isoamylase. Oligosaccharide binding was modeled for branching enzyme using the enzyme-oligosaccharide complex structures of various alpha-amylases and cyclodextrin glucanotransferase and residues were implicated in oligosaccharide binding. While most of the oligosaccharides modeled well in the branching enzyme structure, an approximate 50 degrees rotation between two of the glucose units was required to avoid steric clashes with Trp(298) of branching enzyme. A similar rotation was observed in the mammalian alpha-amylase structure caused by an equivalent tryptophan residue in this structure. It appears that there are two binding modes for oligosaccharides in these structures depending on the identity and location of this aromatic residue.

Selected figure(s)

Figure 2.
Fig. 2. Ribbon depiction of the x-ray crystal structure of E. coli BE truncated at amino acid 113. Residues involved in BE catalysis are shown in green, with atoms colored by type: red, oxygen; green, carbon; blue, nitrogen. Red indicates the NH[2]-terminal domain; orange indicates the central / barrel catalytic domain; and blue indicates the COOH-terminal domain. This and all other depictions of the structure were made using RIBBONS (39).

Figure 6.
Fig. 6. Electrostatic potential surface picture of BE looking down the barrel (a) and rotated 180^o (b). The EPS calculation corresponds to 10 kT/e for the blue color, 10 kT/e for red, and an EPS ~0 is white, where 10 kT ~6 kcal/mol. EPS calculation and figure were made using GRASP (40).

The above figures are reprinted by permission from the ASBMB: J Biol Chem (2002, 277, 42164-42170) copyright 2002.

Figures were selected by an automated process.