PDBsum entry: 1g5a

Transferase

PDB id: 1g5a

Contents

Protein chain

628 a.a. *

Ligands

TRS

EPE

Metals

_NA

Waters ×751

* Residue conservation analysis

PDB id:

1g5a

Name:

Transferase

Title:

Amylosucrase from neisseria polysaccharea

Structure:

Amylosucrase. Chain: a. Engineered: yes

Source:

Neisseria polysaccharea. Organism_taxid: 489. Expressed in: escherichia coli. Expression_system_taxid: 562

Resolution:

1.40Å R-factor: 0.189 R-free: 0.204

Authors:

L.K.Skov,O.Mirza,A.Henriksen,G.P.De Montalk,M.Remaud-Simeon, P.Sarcabal,R.-M.Willemot,P.Monsan,M.Gajhede

Key ref:

L.K.Skov et al. (2001). Amylosucrase, a glucan-synthesizing enzyme from the alpha-amylase family. J Biol Chem, 276, 25273-25278. PubMed id: 11306569 DOI: 10.1074/jbc.M010998200

Date:

31-Oct-00 Release date: 31-Oct-01

Protein chain

Q9ZEU2  (AMYS_NEIPO) -  Amylosucrase

Seq: 636 a.a.

Struc: 628 a.a.*

* PDB and UniProt seqs differ at 5 residue positions (black crosses)

Enzyme reactions

• Enzyme class: E.C.2.4.1.4 - Amylosucrase.
• Reaction: Sucrose + ((1->4)-alpha-D-glucosyl)(n) = D-fructose + ((1->4)-alpha-D- glucosyl)(n+1)

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

 Gene Ontology (GO) functional annotation 

• Cellular component: extracellular region (1 term)
• Biological process: carbohydrate metabolic process (1 term)
• Biochemical function: catalytic activity (5 terms)

Added reference

DOI no: 10.1074/jbc.M010998200

J Biol Chem 276:25273-25278 (2001)

PubMed id: 11306569

Amylosucrase, a glucan-synthesizing enzyme from the alpha-amylase family.

L.K.Skov, O.Mirza, A.Henriksen, G.P.De Montalk, M.Remaud-Simeon, P.Sarçabal, R.M.Willemot, P.Monsan, M.Gajhede.

ABSTRACT

Amylosucrase (E.C. 2.4.1.4) is a member of Family 13 of the glycoside hydrolases (the alpha-amylases), although its biological function is the synthesis of amylose-like polymers from sucrose. The structure of amylosucrase from Neisseria polysaccharea is divided into five domains: an all helical N-terminal domain that is not similar to any known fold, a (beta/alpha)(8)-barrel A-domain, B- and B'-domains displaying alpha/beta-structure, and a C-terminal eight-stranded beta-sheet domain. In contrast to other Family 13 hydrolases that have the active site in the bottom of a large cleft, the active site of amylosucrase is at the bottom of a pocket at the molecular surface. A substrate binding site resembling the amylase 2 subsite is not found in amylosucrase. The site is blocked by a salt bridge between residues in the second and eight loops of the (beta/alpha)(8)-barrel. The result is an exo-acting enzyme. Loop 7 in the amylosucrase barrel is prolonged compared with the loop structure found in other hydrolases, and this insertion (forming domain B') is suggested to be important for the polymer synthase activity of the enzyme. The topology of the B'-domain creates an active site entrance with several ravines in the molecular surface that could be used specifically by the substrates/products (sucrose, glucan polymer, and fructose) that have to get in and out of the active site pocket.

Selected figure(s)

Figure 1.
Fig. 1. Schematic representation of the AS structure with labeling and color-coding of the five domains. N, dark blue; A, light blue; B, yellow; B', magenta; and C, red. The two catalytically active residues (Asp^286 and Glu^328) are also shown. They are located at the end of the barrel -strand 4 and at the tip of -strand 5, respectively. The figure was produced with MOLSCRIPT (36) and Raster3D (37).

Figure 6.
Fig. 6. Drawing of the solvent accessible surface of AS near the pocket opening. The B'-domain is colored dark gray. The O4L of the superimposed modified acarbose is colored white indicating the positions of the TAKA-amylase subsites.

The above figures are reprinted by permission from the ASBMB: J Biol Chem (2001, 276, 25273-25278) copyright 2001.

Figures were selected by an automated process.