PDBsum entry: 2vnc

Hydrolase

PDB-id: 2vnc

Main view

Contents

Description

Header details

Header records

References

PROCHECK

Protein chains

699 a.a. *

Waters ×130

* Residue conservation analysis

Tools

Clefts Calculation

Bottom view	Right view

PDB id:

2vnc

Name:

Hydrolase

Title:

Crystal structure of glycogen debranching enzyme trex from sulfolobus solfataricus

Structure:

Glycogen operon protein glgx. Chain: a, b. Synonym: glycogen debranching enzyme, trex. Engineered: yes. Other_details: disulfide bond between a 254 and a 261

Source:

Sulfolobus solfataricus. Organism_taxid: 2287. Expressed in: escherichia coli. Expression_system_taxid: 562

UniProt:

Chains A, B: P95868 (P95868_SULSO)

Seq:

Struc:

Seq:

Struc:

Seq:

718 a.a.

Struc:

699 a.a.

Key:

PfamA domain

Secondary structure

Resolution:

3.0Å

R-factor:

0.218

R-free:

0.287

Authors:

H.-N.Song,S.-M.Yoon,H.-J.Cha,K.-H.Park,E.-J.Woo

Key ref:

E.J.Woo et al. (2008). Structural insight into the bifunctional mechanism of the glycogen-debranching enzyme TreX from the archaeon Sulfolobus solfataricus.. J Biol Chem, 283, 28641-28648. [PubMed id: 18703518] [DOI: 10.1074/jbc.M802560200]

Date:

04-Feb-08

Release date:

29-Jul-08

Related entries:

2vuy crystal structure of glycogen debranching exzyme trex from sulfolobus solfatarius
2vr5 crystal structure of trex from sulfolobus solfataricus in complex with acarbose intermediate and glucose
2vnb crystal structure of glycogen debranching enzyme trex from sulfolobus solfatarius

Quick_links

Procheck

Clefts

Surface

Key reference

DOI no: 10.1074/jbc.M802560200

J Biol Chem 283:28641-28648 (2008)

PubMed id: 18703518

Structural insight into the bifunctional mechanism of the glycogen-debranching enzyme TreX from the archaeon Sulfolobus solfataricus.

E.J.Woo, S.Lee, H.Cha, J.T.Park, S.M.Yoon, H.N.Song, K.H.Park.

ABSTRACT

TreX is an archaeal glycogen-debranching enzyme that exists in two oligomeric states in solution, as a dimer and tetramer. Unlike its homologs, TreX from Sulfolobus solfataricus shows dual activities for alpha-1,4-transferase and alpha-1,6-glucosidase. To understand this bifunctional mechanism, we determined the crystal structure of TreX in complex with an acarbose ligand. The acarbose intermediate was covalently bound to Asp363, occupying subsites -1 to -3. Although generally similar to the monomeric structure of isoamylase, TreX exhibits two different active-site configurations depending on its oligomeric state. The N terminus of one subunit is located at the active site of the other molecule, resulting in a reshaping of the active site in the tetramer. This is accompanied by a large shift in the "flexible loop" (amino acids 399-416), creating connected holes inside the tetramer. Mutations in the N-terminal region result in a sharp increase in alpha-1,4-transferase activity and a reduced level of alpha-1,6-glucosidase activity. On the basis of geometrical analysis of the active site and mutational study, we suggest that the structural lid (acids 99-97) at the active site generated by the tetramerization is closely associated with the bifunctionality and in particular with the alpha-1,4-transferase activity. These results provide a structural basis for the modulation of activities upon TreX oligomerization that may represent a common mode of action for other glycogen-debranching enzymes in higher organisms.